diff --git a/utils/testrunner/SourceMapSupport.js b/utils/testrunner/SourceMapSupport.js
index ae8933c55e..2cabccc005 100644
--- a/utils/testrunner/SourceMapSupport.js
+++ b/utils/testrunner/SourceMapSupport.js
@@ -27,6 +27,8 @@ class SourceMapSupport {
   }
 
   async rewriteStackTraceWithSourceMaps(error) {
+    if (!error.stack || typeof error.stack !== 'string')
+      return;
     const stackFrames = error.stack.split('\n');
     for (let i = 0; i < stackFrames.length; ++i) {
       const stackFrame = stackFrames[i];