ignore-list published sources if they have have a sourcemap

This shouldn't affect most users since in those case
these files would be inside node_modules/ and therefore
ignore-listed by default.

The only exception I can think of is setups where
modules are not inside node_modules/ but inside
another folder (Yarn Berry has such on option).

It's mostly targetted at our own testing where the
Next.js installation may be symlinked and therefore
not point into node_modules.

Webpack-bundled code may not be affected due to
https://linear.app/vercel/issue/NDX-464.

Author: eps1lon

packages/next/taskfile-swc.js

@@ -166,11 +166,24 @@ if ((typeof exports.default === 'function' || (typeof exports.default === 'objec
 
         output.code += Buffer.from(`\n//# sourceMappingURL=${map}`)
 
+        const sourceMapPayload = JSON.parse(output.map)
+        if ('ignoreList' in sourceMapPayload) {
+          throw new Error(
+            'SWC already sets an ignoreList. We may no longer need to manually set ignoreList.'
+          )
+        }
+        // ignore-list everything
+        sourceMapPayload.ignoreList = sourceMapPayload.sources.map(
+          (source, sourceIndex) => {
+            return sourceIndex
+          }
+        )
+
         // add sourcemap to `files` array
         this._.files.push({
           base: map,
           dir: file.dir,
-          data: Buffer.from(output.map),
+          data: Buffer.from(JSON.stringify(sourceMapPayload)),
         })
       }