Bug 1639111 - Fallback on error.name in DevTools actor error handling r=davidwalsh,ochameau

Differential Revision: https://phabricator.services.mozilla.com/D75902

devtools/shared/protocol/Actor.js

@@ -95,9 +95,12 @@ class Actor extends Pool {
     if (error.stack) {
       console.error(error.stack);
     }
+
     this.conn.send({
       from: this.actorID,
-      error: error.error || "unknownError",
+      // error.error -> errors created using the throwError() helper
+      // error.name -> errors created using `new Error` or Components.exception
+      error: error.error || error.name || "unknownError",
       message: error.message,
     });
   }