diff --git a/07_js-debug/faq/reference-error.ts b/07_js-debug/faq/reference-error.ts
index 5a24250..a6029df 100644
--- a/07_js-debug/faq/reference-error.ts
+++ b/07_js-debug/faq/reference-error.ts
@@ -27,4 +27,10 @@
   // }
 
   greet('John Wick');
+
+  // function divide(a, b) {
+  //   return a / b;
+  // }
+
+  // console.log(divide(10)); // Expected 2 arguments, but got 1.
 }
diff --git a/07_js-debug/unterricht/tag41/04_error-types/03_type-error.html b/07_js-debug/unterricht/tag41/04_error-types/03_type-error.html
new file mode 100644
index 0000000..ccd9d2f
--- /dev/null
+++ b/07_js-debug/unterricht/tag41/04_error-types/03_type-error.html
@@ -0,0 +1,44 @@
+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Type Error</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+    <script src="04_type-error.js"></script>
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>Type Error</h1>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      {
+        NodeList.prototype.__proto__ = Array.prototype;
+
+        const Math = 123;
+        // console.log(Math.sin()); // TypeError: Math.sin is not a function
+        // console.log(Math.PI); // undefined
+
+        const x = 5;
+        // console.log(x.toUpperCase()); // TypeError: x.toUpperCase is not a function
+
+        const resultSum = '150';
+
+        // console.log(resultSum.toFixed(2)); // TypeError: resultSum.toFixed is not a function
+        console.log(Number(resultSum).toFixed(2)); //=> '150.00'
+
+        function greet(name) {
+          console.log('Hello, ' + name); // => 'Hello, 42' <- implizite Typkonvertierung
+        }
+
+        console.log(3 <= '3px'); // <- implizite Typkonvertierung -> 3 <= NaN -> false
+
+        greet(42);
+      }
+    </script>
+  </body>
+</html>
diff --git a/07_js-debug/unterricht/tag41/04_error-types/04_type-error.js b/07_js-debug/unterricht/tag41/04_error-types/04_type-error.js
new file mode 100644
index 0000000..73da071
--- /dev/null
+++ b/07_js-debug/unterricht/tag41/04_error-types/04_type-error.js
@@ -0,0 +1,12 @@
+"use strict";
+{
+    function greet(name) {
+        console.log('Hello, ' + name);
+    }
+    function displayCar(car) {
+        console.log('Brand: ' + car.brand + ', Model: ' + car.model);
+    }
+    const myCar = { name: 'Toyota', model: 'Camry' };
+    greet('11');
+    displayCar({ brand: 'Honda', model: 'E' });
+}
diff --git a/07_js-debug/unterricht/tag41/04_error-types/04_type-error.ts b/07_js-debug/unterricht/tag41/04_error-types/04_type-error.ts
new file mode 100644
index 0000000..1eec014
--- /dev/null
+++ b/07_js-debug/unterricht/tag41/04_error-types/04_type-error.ts
@@ -0,0 +1,23 @@
+{
+  interface Car {
+    brand: string;
+    model: string;
+  }
+
+  function greet(name: string) {
+    console.log('Hello, ' + name);
+  }
+
+  function displayCar(car: Car) {
+    console.log('Brand: ' + car.brand + ', Model: ' + car.model);
+  }
+
+  const myCar = { name: 'Toyota', model: 'Camry' };
+
+  /* greet(42); //  => TypeError: Argument of type 'number' is not assignable to parameter of type 'string' */
+
+  greet('11');
+
+  /* displayCar(myCar); // => TypeError: Argument of type '{ name: string; model: string; }' is not assignable to parameter of type 'Car'. Property 'brand' is missing in type '{ name: string; model: string; }' but required in type 'Car' */
+  displayCar({ brand: 'Honda', model: 'E' });
+}
diff --git a/07_js-debug/unterricht/tag41/04_error-types/package-lock.json b/07_js-debug/unterricht/tag41/04_error-types/package-lock.json
new file mode 100644
index 0000000..ff8c471
--- /dev/null
+++ b/07_js-debug/unterricht/tag41/04_error-types/package-lock.json
@@ -0,0 +1,390 @@
+{
+  "name": "04_error-types",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "04_error-types",
+      "version": "1.0.0",
+      "devDependencies": {
+        "typescript": "^7.0.2"
+      }
+    },
+    "node_modules/@typescript/typescript-aix-ppc64": {
+      "version": "7.0.2",
+      "resolved": "https://registry.npmjs.org/@typescript/typescript-aix-ppc64/-/typescript-aix-ppc64-7.0.2.tgz",
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+      "cpu": [
+        "ppc64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "aix"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-darwin-arm64": {
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+      "resolved": "https://registry.npmjs.org/@typescript/typescript-darwin-arm64/-/typescript-darwin-arm64-7.0.2.tgz",
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+      "cpu": [
+        "arm64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-darwin-x64": {
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+      "resolved": "https://registry.npmjs.org/@typescript/typescript-darwin-x64/-/typescript-darwin-x64-7.0.2.tgz",
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+        "@typescript/typescript-linux-loong64": "7.0.2",
+        "@typescript/typescript-linux-mips64el": "7.0.2",
+        "@typescript/typescript-linux-ppc64": "7.0.2",
+        "@typescript/typescript-linux-riscv64": "7.0.2",
+        "@typescript/typescript-linux-s390x": "7.0.2",
+        "@typescript/typescript-linux-x64": "7.0.2",
+        "@typescript/typescript-netbsd-arm64": "7.0.2",
+        "@typescript/typescript-netbsd-x64": "7.0.2",
+        "@typescript/typescript-openbsd-arm64": "7.0.2",
+        "@typescript/typescript-openbsd-x64": "7.0.2",
+        "@typescript/typescript-sunos-x64": "7.0.2",
+        "@typescript/typescript-win32-arm64": "7.0.2",
+        "@typescript/typescript-win32-x64": "7.0.2"
+      }
+    }
+  }
+}
diff --git a/07_js-debug/unterricht/tag41/04_error-types/package.json b/07_js-debug/unterricht/tag41/04_error-types/package.json
new file mode 100644
index 0000000..0673e45
--- /dev/null
+++ b/07_js-debug/unterricht/tag41/04_error-types/package.json
@@ -0,0 +1,14 @@
+{
+  "name": "04_error-types",
+  "version": "1.0.0",
+  "description": "",
+  "main": "04_type-error.js",
+  "scripts": {
+    "start": "npx tsc 04_type-error.ts --removeComments"
+  },
+  "keywords": [],
+  "type": "commonjs",
+  "devDependencies": {
+    "typescript": "^7.0.2"
+  }
+}
diff --git a/07_js-debug/unterricht/tag41/05_logical-error/logical-error.html b/07_js-debug/unterricht/tag41/05_logical-error/logical-error.html
new file mode 100644
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+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Logical Error</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js"></script>
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>Logical Error</h1>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      {
+        const n = 10;
+
+        if (n % 2 === 0) {
+          console.log('odd'); // Annahme vertauscht
+        } else {
+          console.log('even');
+        }
+
+        console.log(_.range(3)); // => [0,1,2]
+        console.log(_.range(1, 3)); // => [1,2]
+        console.log(_.range(2, 8, 2)); // => [2,4 6]
+
+        // const evenNumbers = _.range(11).filter((n) => n % 2);
+        const evenNumbers = _.range(11).filter((n) => n % 2 === 0);
+
+        console.log('evenNumbers:', evenNumbers);
+
+        // [x]: Ist die Jahreszahl ohne Rest durch 4 teilbar, ist es ein Schaltjahr (z.B. 2024).
+        // [x]: Ist die Jahreszahl durch 100 teilbar, ist es kein Schaltjahr (z.B. 1900).
+        // [x]: Ist die Jahreszahl durch 400 teilbar, ist es doch ein Schaltjahr (z.B. 2000).
+
+        // function isLeapYear(year) {
+        //   if (year % 4 === 0) {
+        //     return true;
+        //   } else if (year % 100 === 0) {
+        //     return true;
+        //   } else if (year % 400 === 0) {
+        //     return true;
+        //   } else {
+        //     return false;
+        //   }
+        // }
+
+        const isLeapYear = (year) => {
+          //   if ((year % 4 === 0 && year % 100 !== 0) || year % 400 === 0) {
+          //     return true;
+          //   } else {
+          //     return false;
+          //   }
+
+          return (!isNaN(year) && year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
+        };
+
+        // Test cases
+        console.log(isLeapYear(2020)); // => true, Expected output: true (leap year)
+        console.log(isLeapYear(1900)); // => true, Expected output: false (not a leap year)
+        console.log(isLeapYear(2000)); // => true, Expected output: true (leap year)
+
+        // ==========
+
+        // function printCharacters(str) {
+        //   console.log(str[1] + str[4] + str[6]);
+        // }
+
+        // function solve(str) {
+        //   printCharacters(str);
+        // }
+
+        // solve('Release a new iPhone every year'); // => 'eae', Expected Output: 'Res'
+
+        function printCharacters(str) {
+          console.log(str[0] + str[3] + str[5]);
+        }
+
+        function solve(str) {
+          printCharacters(str);
+        }
+
+        solve('Release a new iPhone every year'); // => 'Res'
+
+        // =============
+        // // Incorrect index example
+        // function findAverageLength(words) {
+        //   if (words.length === 0) {
+        //     return 0;
+        //   }
+
+        //   let totalLength = 0;
+
+        //   for (let i = 1; i < words.length; i++) {
+        //     if (typeof words[i] === 'string') {
+        //       totalLength += words[i].length;
+        //     }
+        //   }
+
+        //   return totalLength / words.length;
+        // }
+
+        // const words = ['apple', 'banana', 'orange'];
+        // console.log(findAverageLength(words)); // 4 -> Expected output: 5.6666...
+
+        // Incorrect index example
+        function findAverageLength(words) {
+          if (words.length === 0) {
+            return 0;
+          }
+
+          let totalLength = 0;
+
+          for (let i = 0; i < words.length; i++) {
+            if (typeof words[i] === 'string') {
+              totalLength += words[i].length;
+            }
+          }
+
+          return totalLength / words.length;
+        }
+
+        const words = ['apple', 'banana', 'orange'];
+        console.time('for() avg length');
+        console.log(findAverageLength(words)); // 4 -> Expected output: 5.6666...
+        console.timeEnd('for() avg length');
+
+        console.time('join() avg length');
+        console.log(words.join('').length / words.length);
+        console.timeEnd('join() avg length');
+      }
+    </script>
+  </body>
+</html>
diff --git a/07_js-debug/unterricht/tag41/06_demo-form-bug.zip b/07_js-debug/unterricht/tag41/06_demo-form-bug.zip
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diff --git a/07_js-debug/unterricht/tag41/06_demo-form-bug/assets/js/main.js b/07_js-debug/unterricht/tag41/06_demo-form-bug/assets/js/main.js
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+'use strict';
+
+(() => {
+  // ===== DOM =====
+  const DOM = {
+    calculateForm: document.querySelector('#calculateForm'),
+    firstNumberInput: document.querySelector('#firstNumber'),
+    secondNumberInput: document.querySelector('#secondNumber'),
+    result: document.querySelector('#result'),
+  };
+
+  // ===== INIT =====
+  const init = () => {
+    DOM.calculateForm.addEventListener('submit', handleFormSubmit);
+  };
+
+  // ===== EVENT HANDLERS =====
+  function handleFormSubmit(e) {
+    e.preventDefault();
+
+    if (checkIfInputsAreEmpty(DOM.firstNumberInput, DOM.secondNumberInput)) {
+      alert('Please enter a number in both fields');
+      return;
+    }
+
+    const num1 = getNumberValue(DOM.firstNumberInput);
+    const num2 = getNumberValue(DOM.secondNumberInput);
+
+    const sum = add(num1, num2);
+
+    displayResult(sum);
+
+    DOM.calculateForm.reset();
+  }
+
+  // ===== FUNCTIONS =====
+  function checkIfInputsAreEmpty(inputOne, inputTwo) {
+    if (inputOne.value && inputTwo.value) {
+      return false;
+    } else {
+      return true;
+    }
+  }
+
+  function getNumberValue(input) {
+    return input.value;
+  }
+
+  function add(a, b) {
+    return a + b;
+  }
+
+  function displayResult(result) {
+    DOM.result.textContent = result;
+  }
+
+  // ===== CALL INIT =====
+  init();
+})();
diff --git a/07_js-debug/unterricht/tag41/06_demo-form-bug/index.html b/07_js-debug/unterricht/tag41/06_demo-form-bug/index.html
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--- /dev/null
+++ b/07_js-debug/unterricht/tag41/06_demo-form-bug/index.html
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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Debugging Demo</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+    <script src="js/assets/main.js" defer></script>
+  </head>
+  <body>
+    <div class="container py-5">
+      <h1>Debugging Demo</h1>
+
+      <form id="calculateForm" class="mt-4">
+        <div class="col col-12 col-sm-10 col-lg-6">
+          <div class="row mb-3 align-items-center">
+            <label for="firstNumber" class="col-md-3 col-form-label">Number #1:</label>
+            <div class="col-sm-8">
+              <input type="number" id="firstNumber" name="firstNumber" class="form-control" required />
+            </div>
+          </div>
+        </div>
+
+        <div class="col col-12 col-sm-10 col-lg-6">
+          <div class="row mb-3 align-items-center">
+            <label for="secondNumber" class="col-md-3 col-form-label">Number #2:</label>
+            <div class="col-sm-8">
+              <input type="number" id="secondNumber" name="secondNumber" class="form-control" required />
+            </div>
+          </div>
+        </div>
+
+        <div class="mt-4 w-100">
+          <button type="submit" id="calculateBtn" class="btn btn-primary">Add Numbers</button>
+        </div>
+      </form>
+
+      <div class="alert alert-light mt-4"><strong>Result</strong>: <span id="result"></span></div>
+    </div>
+  </body>
+</html>