[bug]Nested import json file in vite.config.ts no more working since vite 2.1.0.

[Ynewtime]

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Describe the bug

Nested import json file in vite.config.ts no more working since vite 2.1.0.

Reproduction

Repo: https://github.com/Ynewtime/import-json-fail

1. npm init @vitejs/app
2. Create a config/config.json file and a src/config.ts file importing the previous one
3. import src/config.ts in vite.config.ts
4. yarn dev

System Info

• vite version: 2.1.0
• Operating System: MacBook Air (M1, 2020)
• Node version: v15.11.0
• Package manager (npm/yarn/pnpm) and version: pnpm 5.18.7

Logs (Optional if provided reproduction)

1. Run vite or vite build with the --debug flag.
2. Provide the error log here.

[yyx990803]

/cc @egoist I believe this is caused by the switch to bundling config with esbuild.