Handle the case where both `currPos.left` and `currPos.right` are null in `YText::deleteText` to prevent error `Cannot read properties of null (reading 'parent')` . Fixes https://github.com/yjs/yjs/issues/504.
Handle the case where both `currPos.left` and `currPos.right` are null in `YText::deleteText` to prevent error `Cannot read properties of null (reading 'parent')` . Fixes https://github.com/yjs/yjs/issues/504.