diff --git a/packages/core/package.json b/packages/core/package.json
index 1bfe481a6..ff76a1a08 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -30,5 +30,6 @@
   "license": "MIT",
   "publishConfig": {
     "access": "public"
-  }
+  },
+  "sideEffects": false
 }
diff --git a/packages/core/src/polyfills/report-error-polyfill.ts b/packages/core/src/polyfills/report-error-polyfill.ts
deleted file mode 100644
index e911d4085..000000000
--- a/packages/core/src/polyfills/report-error-polyfill.ts
+++ /dev/null
@@ -1,13 +0,0 @@
-import { reportError } from '../com/index.js';
-
-/**
- * This polyfill is not essential for the engine itself. But applications built
- * on the engine may require this polyfill to correctly report initialization
- * errors in older browsers.
- * Ideally, the engine should offer a mechanism allowing applications to
- * initialize necessary polyfills before the evaluation of feature files begins.
- * But so far we only need this single polyfill.
- */
-if (globalThis.reportError === undefined) {
-    globalThis.reportError = reportError;
-}
diff --git a/packages/core/src/runtime-main.ts b/packages/core/src/runtime-main.ts
index 7661feadc..6952ef509 100644
--- a/packages/core/src/runtime-main.ts
+++ b/packages/core/src/runtime-main.ts
@@ -1,5 +1,3 @@
-import './polyfills/report-error-polyfill.js';
-
 import type { IRunOptions, TopLevelConfig } from './types.js';
 import type { AnyEnvironment } from './entities/index.js';
 import { FeatureLoadersRegistry, IFeatureLoader } from './run-engine-app.js';
diff --git a/packages/engine-cli/package.json b/packages/engine-cli/package.json
index f1e8cee6d..d187bf3a0 100644
--- a/packages/engine-cli/package.json
+++ b/packages/engine-cli/package.json
@@ -41,5 +41,6 @@
   "license": "MIT",
   "publishConfig": {
     "access": "public"
-  }
+  },
+  "sideEffects": false
 }
diff --git a/packages/runtime-node/package.json b/packages/runtime-node/package.json
index c19e185ef..2dec733fe 100644
--- a/packages/runtime-node/package.json
+++ b/packages/runtime-node/package.json
@@ -32,5 +32,6 @@
   "license": "MIT",
   "publishConfig": {
     "access": "public"
-  }
+  },
+  "sideEffects": false
 }
diff --git a/packages/test-kit/package.json b/packages/test-kit/package.json
index 8dea56dcb..fbbb14b3b 100644
--- a/packages/test-kit/package.json
+++ b/packages/test-kit/package.json
@@ -37,5 +37,6 @@
   "license": "MIT",
   "publishConfig": {
     "access": "public"
-  }
+  },
+  "sideEffects": false
 }