--- a/toolkit/components/extensions/Extension.jsm
+++ b/toolkit/components/extensions/Extension.jsm
@@ -1512,18 +1512,20 @@ this.Extension = class extends Extension
       GlobalManager.init(this);
 
       Management.emit("startup", this);
 
       return this.runManifest(this.manifest);
     }).then(() => {
       Management.emit("ready", this);
     }).catch(e => {
-      dump(`Extension error: ${e.message} ${e.filename || e.fileName}:${e.lineNumber} :: ${e.stack || new Error().stack}\n`);
-      Cu.reportError(e);
+      if (e instanceof Error) {
+        dump(`Extension '${this.id}' error: ${e.message} ${e.filename || e.fileName}:${e.lineNumber} :: ${e.stack || new Error().stack}\n`);
+        Cu.reportError(e);
+      }
 
       if (started) {
         ExtensionManagement.shutdownExtension(this.uuid);
       }
 
       this.cleanupGeneratedFile();
 
       throw e;