fix: caret error on incorrect final word (@Positiveoo1) (#8191)

Closes #8180

!nuf

Author: Positiveoo1

frontend/src/ts/elements/caret.ts

@@ -395,14 +395,21 @@ export class Caret {
     isDirectionReversed: boolean;
   }): { left: number; top: number; width: number } {
     const letters = options.word?.qsa("letter");
-    let letter;
-    if (!letters?.length || !(letter = letters[options.letterIndex])) {
-      // maybe we should return null here instead of throwing
+
+    if (letters.length === 0) {
       throw new Error(
         "Caret getTargetPositionAndWidth: no letters found in word",
       );
     }
 
+    let letter = letters[options.letterIndex] ?? letters[letters.length - 1];
+
+    if (!letter) {
+      throw new Error(
+        `Caret getTargetPositionAndWidth: letter not found for index ${options.letterIndex}`,
+      );
+    }
+
     if (caretDebug) {
       if (this.id === "paceCaret") {
         for (const l of document.querySelectorAll(".word letter")) {