tsconfig.json

{
  "compilerOptions": {
    "experimentalDecorators": true,
    "jsx": "react",
    "allowJs": true,
    "baseUrl": "./src",
    // outDir is declared even if it's unused to avoid a class of mixed-js errors
    "outDir": "./build",
    "target": "esnext",
    "noImplicitThis": true,
    "moduleResolution": "node",
    "module": "commonjs",
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "strict": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noImplicitAny": false,
    "skipLibCheck": true,
    "strictNullChecks": false, // TODO: enable (default enabled under `strict`, so just remove this line)
    "paths": {
      // path mappings are mirrored in the jest config in package.json. if you
      // change them here, update them there as well!
      "~/*": ["./*"]
    }
  },
  "include": ["app/**/*.ts", "app/**/*.tsx"]
}