Fix fault detail when ext throws non-error object

lib/extension-wrapper.js

@@ -26,15 +26,22 @@ function errorToFault(err) {
   if (!err)
     return null;
 
-  return {
+  if (!err.name)
+    return {code: "ext", message: `${err}`};
+
+  let fault = {
     code: `ext.${err.name}`,
     message: err.message,
     detail: {
       name: err.name,
-      message: err.message,
-      stack: err.stack
-    }
+      message: err.message
     }
+  };
+
+  if (err.stack)
+    fault.detail.stack = err.stack;
+
+  return fault;
 }
 
 process.on("uncaughtException", function(err) {