feat: add loopback when finding a valid node during a keyboard drag (RaspberryPiFoundation#409)

* fix: add looping for finding the next/previous node during movement

* chore: fix lint in undo_redo.ts

* feat: use core looping feature

Author: rachel-fenichel

src/actions/undo_redo.ts

@@ -4,17 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import {
-  ShortcutRegistry,
-  utils as BlocklyUtils,
-  ShortcutItems,
-  WorkspaceSvg,
-} from 'blockly/core';
-
-import * as Constants from '../constants';
-import type {Navigation} from '../navigation';
-
-const KeyCodes = BlocklyUtils.KeyCodes;
+import {ShortcutRegistry, ShortcutItems, WorkspaceSvg} from 'blockly/core';
 
 /**
  * Class for registering a shortcut for undo/redo actions.

src/keyboard_drag_strategy.ts

@@ -144,21 +144,20 @@ export class KeyboardDragStrategy extends dragging.BlockDragStrategy {
     const cursor = draggingBlock.workspace.getCursor() as LineCursor;
     if (!cursor) return null;
 
+    // Helper function for traversal.
+    function isConnection(node: ASTNode | null): boolean {
+      return !!node && node.isConnection();
+    }
+
     const connectionChecker = draggingBlock.workspace.connectionChecker;
     let candidateConnection: ConnectionCandidate | null = null;
     let potential: ASTNode | null = this.searchNode;
     const dir = this.currentDragDirection;
     while (potential && !candidateConnection) {
       if (dir === Direction.Up || dir === Direction.Left) {
-        potential = cursor.getPreviousNode(potential, (node) => {
-          // @ts-expect-error isConnectionType is private.
-          return node && ASTNode.isConnectionType(node.getType());
-        });
+        potential = cursor.getPreviousNode(potential, isConnection, true);
       } else if (dir === Direction.Down || dir === Direction.Right) {
-        potential = cursor.getNextNode(potential, (node) => {
-          // @ts-expect-error isConnectionType is private.
-          return node && ASTNode.isConnectionType(node.getType());
-        });
+        potential = cursor.getNextNode(potential, isConnection, true);
       }
 
       localConns.forEach((conn: RenderedConnection) => {