[Bitcoin Core] "Cache Size must be at least 4." when trying to save any configuration change

[t11z]

Description

Whenever trying to make any change to the Bitcoin Core configuration using the app's "Advanced Settings" menu, the configuration cannot be saved and the UI responds with the error:

Please fix the following errors and try again:

Cache Size must be at least 4.

Steps to Reproduce

1. Install Bitcoin Core app from Umbrel App Store
2. Open Bitcoin Core app from Umbrel main screen
3. Click on the ••• menu icon
4. Click on Advanced Settings
5. Make any change to the configuration
6. Click on Save and restart Bitcoin node

Expected Behavior

Configuration should be saved and Bitcoin Core should be restarted with new configuration applied.

Actual Behavior

Error message is shown as described above, configuration is not saved and Bitcoin Core is not restarted.

Screenshots