fix rendering bug from addon

Author: SharkPool-SP

blocks_vertical/control.js

@@ -275,9 +275,11 @@ Blockly.Blocks['control_expandableIf'] = {
       if (prevText) prevText.appendField("if");
       else this.appendDummyInput(`TEXTSTART${this.branches_}`).appendField("if");
       const input = this.appendValueInput(`BOOL${this.branches_}`).setCheck("Boolean");
-      input.init();
-      input.initOutlinePath(this.svgGroup_);
-      input.outlinePath.setAttribute('fill', this.getColourTertiary());
+      if (!this.isInsertionMarker_) {
+        input.init();
+        input.initOutlinePath(this.svgGroup_);
+        input.outlinePath.setAttribute('fill', this.getColourTertiary());
+      }
       if (shouldPopulate) this.fillInBlock(input.connection, "checkbox");
       this.appendDummyInput(`TEXTEND${this.branches_}`).appendField("then");