tsconfig.json

{
    "extends": "@tsconfig/svelte/tsconfig.json",
    "compilerOptions": {
        "target": "ESNext",
        "useDefineForClassFields": true,
        "module": "ESNext",
        "resolveJsonModule": true,
        "baseUrl": ".",
        "paths": {
          "$lib": ["./src/lib"],
          "$lib/*": ["./src/lib/*"]
        },
        /**
         * Typecheck JS in `.svelte` and `.js` files by default.
         * Disable checkJs if you'd like to use dynamic types in JS.
         * Note that setting allowJs false does not prevent the use
         * of JS in `.svelte` files.
         */
        "allowJs": true,
        "checkJs": true,
        "isolatedModules": true
    },
    "include": ["src/**/*.d.ts", "src/**/*.ts", "src/**/*.js", "src/**/*.svelte"],
    "references": [{ "path": "./tsconfig.node.json" }]
}