Teacher Tools: No warning appears when there is already unnamed checklist and then create or open checklist

[v-katherine]

Describe the bug
Teacher Tools: No warning appears when there is already unnamed checklist and then create or open checklist

Steps to reproduce the behavior
1.Navigate to MakeCode Teacher Tool (microbit.org).
2.Create a new checklist with unnamed.
3.Create or open an existed checklist, observe.

Actual behavior:
No warning appears.

Expected behavior:
A warning will appear to ask if overwriting it.

Screen Recording:

Additional context:
1.OS: Windows11 iMac Ventura 13.6.6
2.makecode.microbit,org version: 7.0.9
3.Microsoft MakeCode version: 10.0.21

[v-katherine]

Also reproduced in import a checklist when there is already unnamed checklist