js: Do not fail while trying to detect autosubmit element

fixes #5439

(cherry picked from commit 9b63928)

Author: nilmerg

public/js/icinga/behavior/modal.js

@@ -114,7 +114,7 @@
         }
 
         let $autoSubmittedBy;
-        if (typeof event.detail !== 'undefined' && "submittedBy" in event.detail) {
+        if (event.detail !== null && typeof event.detail === 'object' && "submittedBy" in event.detail) {
             $autoSubmittedBy = $(event.detail.submittedBy);
         }
 

public/js/icinga/events.js

@@ -261,7 +261,11 @@
                 }
             }
 
-            if (! $autoSubmittedBy && typeof event.detail !== 'undefined' && "submittedBy" in event.detail) {
+            if (! $autoSubmittedBy
+                && event.detail !== null
+                && typeof event.detail === 'object'
+                && "submittedBy" in event.detail
+            ) {
                 $autoSubmittedBy = $(event.detail.submittedBy);
             }