diff --git a/test/coverage-utils.js b/test/coverage-utils.js
index c1799f261c9..221aaaef4cf 100644
--- a/test/coverage-utils.js
+++ b/test/coverage-utils.js
@@ -37,6 +37,12 @@ const fs = require('fs');
  */
 function traceAPICoverage(apiCoverage, events, className, classType) {
   className = className.substring(0, 1).toLowerCase() + className.substring(1);
+  if (!classType || !classType.prototype) {
+    console.error(
+      `Coverage error: could not find class for ${className}. Is src/api.ts up to date?`
+    );
+    process.exit(1);
+  }
   for (const methodName of Reflect.ownKeys(classType.prototype)) {
     const method = Reflect.get(classType.prototype, methodName);
     if (