fix: harden error handling in lib/cli/run.js

lib/cli/run.js

@@ -369,7 +369,7 @@ exports.handler = async function (argv) {
   try {
     await runMocha(mocha, argv);
   } catch (err) {
-    console.error('\n' + (err.stack || `Error: ${err.message || err}`));
+    console.error('\n Exception during run:', err);
     process.exit(1);
   }
 };