preserve embedded inputs when JOINing a nested expression with an empty list

HISTORY.md

@@ -6,9 +6,13 @@
 * **Notable Changes:**
 * **Notable Fixes:**
     * setting a clone's rotation coordinates shadows its inherited costumes
+    * preserve embedded inputs when JOINing a nested expression with an empty list
 * **Documentation Updates:**
 * **Translation Updates:**
 
+### 2021-12-20
+* blocks, threads: preserve embedded inputs when JOINing a nested expression with an empty list
+
 ### 2021-12-18
 * new dev version
 * objects: shadow (a clone's) costumes when setting its rotation coordinates 

snap.html

@@ -16,8 +16,8 @@
         <script src="src/morphic.js?version=2021-12-10"></script>
         <script src="src/symbols.js?version=2021-03-03"></script>
         <script src="src/widgets.js?version=2021-17-09"></script>
-        <script src="src/blocks.js?version=2021-12-09"></script>
-        <script src="src/threads.js?version=2021-12-15"></script>
+        <script src="src/blocks.js?version=2021-12-20"></script>
+        <script src="src/threads.js?version=2021-12-20"></script>
         <script src="src/objects.js?version=2021-12-18"></script>
         <script src="src/scenes.js?version=2021-11-24"></script>
         <script src="src/gui.js?version=2021-12-18"></script>

src/blocks.js

@@ -160,7 +160,7 @@ CustomCommandBlockMorph, ToggleButtonMorph, DialMorph, SnapExtensions*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.blocks = '2021-December-09';
+modules.blocks = '2021-December-20';
 
 var SyntaxElementMorph;
 var BlockMorph;
@@ -3826,6 +3826,10 @@ BlockMorph.prototype.copyWithInputs = function (inputs) {
         count = 0,
         dflt;
 
+    if (dta.length === 0) {
+        return cpy.reify();
+    }
+
     // restore input slots
     slots.forEach(slt => {
         if (slt instanceof BlockMorph) {

src/threads.js

@@ -64,7 +64,7 @@ SnapExtensions, AlignmentMorph, TextMorph, Cloud, HatBlockMorph*/
 
 /*jshint esversion: 6*/
 
-modules.threads = '2021-December-15';
+modules.threads = '2021-December-20';
 
 var ThreadManager;
 var Process;
@@ -7157,7 +7157,7 @@ Context.prototype.equalTo = function (other) {
 
 Context.prototype.copyWithInputs = function (inputs) {
     return this.expression ?
-        this.expression.copyWithInputs(inputs, this.inputs.slice())
+        this.expression.copyWithInputs(inputs)
         : this;
 };