flatpak-builder silently ignores entries of invalid type in `build-commands` in manifest YAML

[nandedamana]

Checklist

• [X] I agree to follow the Code of Conduct that this project adheres to.
• [X] I have searched the issue tracker for a bug that matches the one I want to file, without success.

flatpak-builder version

1.15.6

Flatpak version

1.4.1

How to reproduce

1. Start a sample flatpak project with a YAML manifest, simple build method, and multiple commands listed under build-commands as an array; make sure the build succeeds
2. Add false as an element in the build-commands array somewhere in the middle (simulating a user adding it meaning the UNIX false command, without realizing it should've been quoted)

Expected Behavior

flatpak-builder should warn that the list contains an element of invalid type (bool instead of string).

Actual Behavior

flatpak-builder silently ignores the bool entry and finishes the build successfully.

Additional Information

No response

[nandedamana]

The issue could be with json_gobject_deserialize().