fix: file processing with --clean for unknown languages

[drgsn]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 37.50000% with 10 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/core/processor.go	37.50%	6 Missing and 4 partials ⚠️

Files with missing lines	Coverage Δ
internal/core/processor.go	88.71% <37.50%> (+2.30%)	⬆️