tsconfig.json

{
    "include": ["src/**/*", "config/**/*"],
    "compilerOptions": {
        "target": "ES2021",

        // Type Checking
        "allowUnreachableCode": false,
        "allowUnusedLabels": false,
        "exactOptionalPropertyTypes": true,
        "noFallthroughCasesInSwitch": true,
        "noImplicitOverride": true,
        "noImplicitReturns": true,
        "noPropertyAccessFromIndexSignature": true,
        "noUncheckedIndexedAccess": true,
        "noUnusedLocals": true,
        "noUnusedParameters": true,
        "strict": true,

        // Modules
        "module": "ES2020",
        "moduleResolution": "node",

        // Emit
        /**
        Svelte Preprocess cannot figure out whether you have a value or a type, so tell TypeScript
        to enforce using `import type` instead of `import` for Types.
        */
        "verbatimModuleSyntax": true,

        /**
        To have warnings/errors of the Svelte compiler at the correct position,
        enable source maps by default.
        */
        "sourceMap": true,

        // JavaScript Support
        "allowJs": true, // TODO Remove once fully migrated

        // Interop Constraints
        "esModuleInterop": true,
        "forceConsistentCasingInFileNames": true,
        "isolatedModules": true
    }
}