tsconfig.json

{
  "compilerOptions": {
    "target": "esnext",
    "module": "esnext",
    "moduleResolution": "node",

    // require `import type` instead fo `import` for types
    // svelte-preprocess apparently needs this
    "importsNotUsedAsValues": "error",
    "isolatedModules": true,

    // To have svelte warnings/errors correct position
    "sourceMap": true,

    "resolveJsonModule": true,

    "noImplicitAny": false,
    "strictNullChecks": false,

    // Prevent type errors
    "types": ["svelte"],
    "typeRoots": ["./node_modules/@types", "./src/types"],

    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "baseUrl": "."
  },
  "include": ["src/**/*.ts", "src/**/*.svelte"]
}