Check for Sentry span before appending header for WebSocket

Fix CODEOCEAN-FRONTEND-2X

app/assets/javascripts/editor/execution.js

@@ -11,10 +11,12 @@ CodeOceanEditorWebsocket = {
       // strip anchor if it is in the url
       sockURL.hash = '';
 
+      if (span) {
         sockURL.searchParams.set('HTTP_SENTRY_TRACE', span.toTraceparent());
         const dynamicContext = this.sentryTransaction.getDynamicSamplingContext();
         const baggage = SentryUtils.dynamicSamplingContextToSentryBaggageHeader(dynamicContext);
         sockURL.searchParams.set('HTTP_BAGGAGE', baggage);
+      }
 
       return sockURL.toString();
   },