Let's try mozilla's fixedCharAt function

commands/drawDesign.cjs

@@ -217,6 +217,7 @@ function charIterate(input) {
 	for (let i = 0; i < stringLength; ++i) {
 		if (surrogatePairs.exec(input.charCodeAt(charIterateState)) !== null) {
 			stringLength--;
+			console.log("Decreasing stringLength variable to", stringLength);
 		}
 	}
 	if (charIterateState == undefined) {