setup-bun/tsconfig.json

{
  "compilerOptions": {
    "outDir": "dist/",
    "lib": ["ESNext"],
    "module": "esnext",
    "target": "ES2018",
    "moduleResolution": "node",
    // "bun-types" is the important part
    "types": ["bun-types"],
    "skipLibCheck": true
  }
}