Pluginval silently succeeds when empty path given to --validate

[sudara]

Noticed this in Release, in CI:

In Debug, it hits an assert:

➜  cmake-build-debug git:(main) ✗ ./modules/pluginval/pluginval_artefacts/Debug/pluginval.app/Contents/MacOS/pluginval --strictness-level 10 --timeout-ms 110000 --verbose --validate ""          
JUCE v8.0.4
JUCE Assertion failure in PluginTests.cpp:53
Started validating: 
Random seed: 0x26a7379
Validation started
	4 Dec 2024 10:49:55pm

Strictness level: 10
SUCCESS

In addition to the assert, it should probably emit an error message and return exit code 1.

[drowaudio]

Agreed, if not plugins are found it should return 1.