Unable to Import MD Files in Astro When Built, but Works During npm run dev

Question

Currently, I'm trying to import MD files in Astro using the following code:

import * as a from '../content/a.md';

This code works perfectly fine when I'm running "npm run dev", but it throws an error during build as follows:

Assigning to rvalue (Note that you need plugins to import files that are not JavaScript)

I've found out that during "npm run dev", it references "declare module '*.md'" in client-base.d.ts.

However, I don't think it's referencing during the build process.

How can I make sure that I can import MD files during the build process in Astro?

I created an md.d.ts file to mimic the declaration in client-base.d.ts:

declare module '*.md' {
    const content: string;
    export default content;
}

I then added the md.d.ts file to my tsconfig.json to include it in the build process:

{
  "extends": "astro/tsconfigs/strict",
  "compilerOptions": {
    "strictNullChecks": true
  },
  "include": [
    "md.d.ts"
  ]
}