--- a/devtools/client/webconsole/webconsole.js
+++ b/devtools/client/webconsole/webconsole.js
@@ -1528,17 +1528,17 @@ WebConsoleFrame.prototype = {
 
     // Add the more info link node to messages that belong to certain categories
     if (scriptError.exceptionDocURL) {
       this.addLearnMoreWarningNode(msgBody, scriptError.exceptionDocURL);
     }
 
     // Collect telemetry data regarding JavaScript errors
     this._telemetry.logKeyed("DEVTOOLS_JAVASCRIPT_ERROR_DISPLAYED",
-                             scriptError.errorMessageName,
+                             scriptError.errorMessageName || "Unknown",
                              true);
 
     if (objectActors.size > 0) {
       node._objectActors = objectActors;
     }
 
     return node;
   },