(core) Fixing bug in token field editor with moving choices.

Summary:
Sometimes when rearranging items in choice editor, user can
put the new item inside last entry element, which is not recognized as
a choice entry.

Test Plan: manual tests

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3519

app/client/lib/TokenField.ts

@@ -525,8 +525,15 @@ export class TokenField<Token extends IToken = IToken> extends Disposable {
 
       // Find the token before which we are inserting the dragged elements. If inserting at the
       // end (just before or over the input box), destToken will be undefined.
-      const index = allTargets.indexOf(ev.target as HTMLElement);
-      if (index < 0) { return; }
+      let index = allTargets.indexOf(ev.target as HTMLElement);
+      if (index < 0) {
+        // Sometimes we are at inner input element of the target (when dragging past the last element).
+        // In this case we need to test the parent.
+        if (ev.target instanceof HTMLInputElement && ev.target.parentElement) {
+          index = allTargets.indexOf(ev.target.parentElement);
+        }
+        if (index < 0) { return; }
+      }
       const destToken: TokenWrap<Token>|undefined = this._tokens.get()[index];
 
       const selection = this._selection.get();