Add guard for error handling

CHANGELOG.md

@@ -1,7 +1,8 @@
 # 2.38.4-0 / Unreleased
 
--   [Changed] #1143 Improve the appearance of vertical connectors of skin XP
--   [Fixed] [#1157](https://github.com/mar10/fancytree/issues/1157) Sporadic error restoring expansion
+- [Changed] #1143 Improve the appearance of vertical connectors of skin XP
+- [Fixed] [#1157](https://github.com/mar10/fancytree/issues/1157) Sporadic error restoring expansion
+- [Fixed] [#1158](https://github.com/mar10/fancytree/issues/1158) Add guard for error handling 
 
 # 2.38.3 / 2023-02-01
 

src/jquery.fancytree.js

@@ -180,7 +180,9 @@
 
 			// #1041: Raised exceptions may not be visible in the browser
 			// console if inside promise chains, so we also print directly:
-			$.ui.fancytree.error(msg);
+			if ($.ui && $.ui.fancytree) {
+				$.ui.fancytree.error(msg);
+			}
 
 			// Throw exception:
 			$.error(msg);