fixed an error display glitch

HISTORY.md

@@ -67,6 +67,7 @@
 * blocks, objects, store: include a representation of the stage as sprite in the "scripts pic" export if it is more than a single one
 * removed some "under construction" markers
 * new release candidate version
+* threads: fixed an error display glitch
 
 ### 2022-07-31
 * threads: fixed #3085 (I hope ^^)

src/threads.js

@@ -65,7 +65,7 @@ StagePickerMorph, CustomBlockDefinition*/
 
 /*jshint esversion: 11, bitwise: false, evil: true*/
 
-modules.threads = '2022-July-31';
+modules.threads = '2022-August-01';
 
 var ThreadManager;
 var Process;
@@ -1242,7 +1242,7 @@ Process.prototype.errorBubble = function (error, element) {
     if (errorIsNested && error.cause !== 'user') {
         if (blockToShow.selector === 'reportGetVar') {
             // if I am a single variable, show my caller in the output.
-            blockToShow = blockToShow.parent;
+            blockToShow = blockToShow.parent || blockToShow;
         }
         errorMorph.children[0].text += `\n${localize('The question came up at')}`;
         errorMorph.children[0].fixLayout();