Add undefined check to getZuulStatus

Change-Id: I65ec78fa4fac5a8a3adabc6d9e51b694c0e56594

src/main/resources/static/zuul-status-view.js

diff --git a/src/main/resources/static/zuul-status-view.js b/src/main/resources/static/zuul-status-view.js
index e5df740..3c8575c 100644
--- a/src/main/resources/static/zuul-status-view.js
+++ b/src/main/resources/static/zuul-status-view.js
@@ -185,6 +185,8 @@
      * @return {Promise} Resolves to a fetch Response object.
      */
     async getZuulStatus(change, revision) {
+      if (!change || !revision) return [];
+
       const response = await this._getReponse(change, revision);
 
       if (response && response.status && response.status === 200) {