`[Bug] Pybricks Beta v3.1.0-beta.5 does not disable the "Run"-button after all open files have been closed

[BertLindeman]

Describe the bug
When no source file is open in the app, the "Run" button should be disabled.
But if a source file is open and then closed (as the last open file), the "Run" button stays active.
No real harm in this situation.
Press of the "run"-button compiles (I think) an empty program or is it the sensor view?
In dev console I only see Downloading 35 bytes.

To reproduce

1. Go to beta.pybricks.com
2. Open any script file (the "Run" button becomes enabled)
3. Close the file (as the last open file)
4. Observe that the "Run" button remains enabled despite no file being open

Expected behavior
The "Run" button should be disabled whenever no source file is open, including after the last open file is closed.

Screenshots
With a file open

No file open anymore

extra info

• pybricks as Chrome app
• chrome Version 153.0.8010.53 (Official Build) (64-bit)
• win11 25H2