improved handling of user-defined errors and errors inside custom blocks

HISTORY.md

@@ -6,6 +6,7 @@
 * **Notable Changes:**
     * same blocks with empty variadic inputs compare as equal regardless of their arity
     * made "When I receive any messagge" non-thread-safe by default (again) to enable tail recursive broadcasts
+    * improved handling of user-defined errors and errors inside custom blocks 
 * **Notable Fixes:**
     * fixed storing the stage name(s)
     * removed distinction between number and string keys in "analyze" 
@@ -20,6 +21,7 @@
 * api: fixed variable binding when broadcasting through the API, thanks, Zak!
 * objects: fixed programmatically hiding palette blocks using the "hide variable" block, thanks, Zak!
 * threads, api: made "When I receive any messagge" non-thread-safe by default (again) to enable tail recursive broadcasts
+* threads, extensions: improved handling of user-defined errors and errors inside custom blocks 
 
 ### 2022-01-02
 * store: fixed storing the stage name(s)

snap.html

@@ -28,7 +28,7 @@
         <script src="src/sketch.js?version=2021-11-03"></script>
         <script src="src/video.js?version=2019-06-27"></script>
         <script src="src/maps.js?version=2021-06-15"></script>
-        <script src="src/extensions.js?version=2022-01-01"></script>
+        <script src="src/extensions.js?version=2022-01-03"></script>
         <script src="src/xml.js?version=2021-07-05"></script>
         <script src="src/store.js?version=2022-01-02"></script>
         <script src="src/locale.js?version=2022-01-03"></script>

src/extensions.js

@@ -33,7 +33,7 @@ Color, Process, contains*/
 
 /*jshint esversion: 11*/
 
-modules.extensions = '2022-January-01';
+modules.extensions = '2022-January-03';
 
 // Global stuff
 
@@ -203,7 +203,7 @@ var SnapExtensions = {
 SnapExtensions.primitives.set(
     'err_error(msg)',
     function (msg) {
-        throw new Error(msg);
+        throw new Error(msg, {cause: 'user'});
     }
 );
 

src/threads.js

@@ -1214,7 +1214,7 @@ Process.prototype.errorBubble = function (error, element) {
     // above the text of error.
     var errorMorph = new AlignmentMorph('column', 5),
         errorIsNested = isNil(element.world()),
-        errorPrefix = errorIsNested ? `${localize('Inside a custom block')}:\n`
+        errorPrefix = errorIsNested ? `${localize('Inside a custom block')}\n`
             : '',
         errorMessage = new TextMorph(
             `${errorPrefix}${localize(error.name)}:\n${localize(error.message)}`,
@@ -1223,16 +1223,18 @@ Process.prototype.errorBubble = function (error, element) {
         blockToShow = element;
 
     errorMorph.add(errorMessage);
-    if (errorIsNested) {
+
+    if (errorIsNested && error.cause !== 'user') {
         if (blockToShow.selector === 'reportGetVar') {
             // if I am a single variable, show my caller in the output.
             blockToShow = blockToShow.parent;
         }
-        errorMorph.text += `\n${localize('The error occured at:')}\n`;
+        errorMorph.children[0].text += `\n${localize('The error occured at')}`;
+        errorMorph.children[0].fixLayout();
         errorMorph.add(blockToShow.fullCopy());
-        errorMorph.fixLayout();
     }
 
+    errorMorph.fixLayout();
     return errorMorph;
 };