tsconfig.json

{
  // This imports all the default Docusaurus types
  "extends": "@docusaurus/tsconfig",

  // All compiler settings MUST go inside this object
  "compilerOptions": {
    // --- Fix for '@theme/Heading' error ---
    "baseUrl": ".",
    "types": [
      "@docusaurus/module-type-aliases",
      "@docusaurus/theme-classic"
    ],

    // --- Fix for the deprecation warning ---
    // I also fixed a small typo here ("ignoreDepregations" -> "ignoreDeprecations")
    "ignoreDeprecations": "5.0",

    // --- All your other settings, now in the right place ---
    "jsx": "react-jsx",
    "lib": ["DOM", "DOM.Iterable", "ESNext"],
    "noEmit": true,
    "resolveJsonModule": true,
    "allowJs": true,
    "strict": false,
    "skipLibCheck": true,
    "moduleResolution": "node"
  },

  // This is correct, it stays at the root
  "exclude": [".docusaurus", "build"]
}