handle (some cases of) extent-less costumes

HISTORY.md

@@ -23,6 +23,7 @@
 * animation library: fixed pen state for GLIDE, thanks, Brian!
 * threads: addressed security issues in the JIT-compiler, thanks, xBZZZZ!
 * gui: show project name in browser tab, thanks, Peter!
+* objects: handle (some cases of) extent-less costumes
 
 ### 2022-03-03
 * SciSnap2 extension update (FFT), thanks, Eckart!

src/objects.js

@@ -3824,6 +3824,10 @@ SpriteMorph.prototype.wearCostume = function (costume, noShadow) {
         y = this.yPosition ? this.yPosition() : null,
         idx = isNil(costume) ? null : this.costumes.asArray().indexOf(costume);
 
+    if (costume && (!costume.width() || !costume.height())) {
+        costume = null;
+        idx = null;
+    }
     this.changed();
     this.costume = costume;
     this.fixLayout();