Stackframe is not cleared in `retireThread`

Expected Behavior

• Thread.stackFrames should be cleared in Sequencer.retireThread.
• It should be checked whether the thread is done before invoking Thread.goToNextBlock.

Actual Behavior

In scratch-vm, Thread.stackFrames are not cleared correctly in Sequencer.retireThread due to typo problems.
https://github.com/scratchfoundation/scratch-editor/blob/a54b373f5e265283ff533d277f00329f9dd8ea03/packages/scratch-vm/src/engine/sequencer.js#L353-L358

It should be this.stackFrames = [];.

After fixing this typo problem, it will lead to another problem: project with edge-activated hat blocks will raise error in reuseStackForNextBlock. (It can be verified in test/integration/stack-click.js)

TypeError: Cannot read properties of undefined (reading 'reuse')

      246 |     reuseStackForNextBlock (blockId: string | null): void {
      247 |         this.stack[this.stack.length - 1] = blockId;
    > 248 |         this.stackFrames[this.stackFrames.length - 1].reuse();
          |                                                       ^
      249 |     }
      250 |
      251 |     /**

      at Thread.reuse [as reuseStackForNextBlock] (src/engine/thread.ts:248:55)
      at Thread.reuseStackForNextBlock [as goToNextBlock] (src/engine/thread.ts:380:14)
      at goToNextBlock (src/engine/runtime.js:2189:24)
          at Array.forEach (<anonymous>)
      at Runtime.forEach [as startHats] (src/engine/runtime.js:2186:20)
      at Runtime.startHats [as _step] (src/engine/runtime.js:2398:22)
      at Timeout._step [as _onTimeout] (src/engine/runtime.js:2973:18)

The problem is caused by Runtime.startHats. After executing the thread, it's status might be Thread.STATUS_DONE and the thread might have been retired, then thread.stack and thread.stackFrame should be empty array. Then function reuseStackForNextBlock will access this.stack[-1] and this.stackFrames[-1], and try to call undefined.reuse(), which will break the program.

https://github.com/scratchfoundation/scratch-editor/blob/a54b373f5e265283ff533d277f00329f9dd8ea03/packages/scratch-vm/src/engine/runtime.js#L1927-L1930

Previously, since this.stackFrames is not cleared and javascript allows assignment to array[-1], vm looks like running well.

Steps to Reproduce

1. Replace this.stackFrame = []; with this.stackFrames = []; in function Sequencer.retireThread.
2. Run test case test/integration/stack-click.js.

Screenshots

None.

System Details

None.

Start in packages/scratch-vm/src/engine/sequencer.js at Sequencer.retireThread and inspect the related flow in packages/scratch-vm/src/engine/runtime.js and Thread.goToNextBlock. Run test/integration/stack-click.js after correcting the stack-frame handling and checking the thread status before advancing. Done means the test passes without the reuseStackForNextBlock undefined error.