Incomplete sourcemap: source file missing

[undecaf]

Description

I am building an ES6 module library with multiple Vue components using rollup and rollup-plugin-terser. Unfortunately, the generated .map file is missing at least one source file. This appears similar to #72 .

Why do I think this is an issue of rollup-plugin-terser?

If I run rollup without terser then the .map file is complete (and the .js is not compressed). Running terser from the command line on these files creates the expected result: a compressed .js file and a complete .map file.

How to reproduce

I have prepared a minimal project demonstrating this issue. Download, unzip and run npm install.

Uncomment terser() in rollup.config.js and npm run build. This builds a library of two simple Vue components (<comp-main> and <comp-aux>) in dist/components.esm.js. Only comp-aux.vue shows up in the sourcemap sources property.

Building a correct sourcemap: remove terser() from rollup.config.js, npm run build and then npm run terser. Now the sourcemap sources property contains both comp-main.vue and comp-aux.vue.

Workaround

Remove terser() from rollup.config.js and run terser automatically after building. This is done by just removing the leading '_' from "_postbuild" in package.json.