build: Disable side-effects for any ./debug-build.ts file (#16929)

- Closes #16846

Author: timfish

dev-packages/rollup-utils/npmHelpers.mjs

@@ -26,6 +26,8 @@ const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
 const packageDotJSON = JSON.parse(fs.readFileSync(path.resolve(process.cwd(), './package.json'), { encoding: 'utf8' }));
 
+const ignoreSideEffects = /[\\\/]debug-build\.ts$/;
+
 export function makeBaseNPMConfig(options = {}) {
   const {
     entrypoints = ['src/index.ts'],
@@ -83,6 +85,17 @@ export function makeBaseNPMConfig(options = {}) {
       interop: 'esModule',
     },
 
+    treeshake: {
+      moduleSideEffects: (id, external) => {
+        if (external === false && ignoreSideEffects.test(id)) {
+          // Tell Rollup this module has no side effects, so it can be tree-shaken
+          return false;
+        }
+
+        return true;
+      }
+    },
+
     plugins: [nodeResolvePlugin, sucrasePlugin, debugBuildStatementReplacePlugin, rrwebBuildPlugin, cleanupPlugin],
 
     // don't include imported modules from outside the package in the final output