tsconfig.json

{
  "compilerOptions": {
    "target": "ESNext",
    "useDefineForClassFields": true,
    "lib": ["ESNext", "DOM", "DOM.Iterable"],
    "module": "esnext",
    "skipLibCheck": true,
    "types": ["node", "vitest/globals"],

    /* Bundler mode */
    "rootDir": ".",
    "baseUrl": "./src",
    "outDir": "./dist",
    "moduleResolution": "bundler",
    // "allowImportingTsExtensions": true,
    // "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
    "jsx": "react-jsx",
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,

    /* Type Checking */
    "strict": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noFallthroughCasesInSwitch": true,
    "noUncheckedIndexedAccess": true, // this should honestly be the default, since you're not guaranteed to get a value when you key into an object
    "exactOptionalPropertyTypes": true // | undefined needs to be explicit
  },
  "include": ["src", "tests"]
}