scaper.scaper_exceptions.ScaperError: Label value must match one of the available labels: []

[CleanPegasus]

I'm getting the following error on trying to merge .wav files from 2 different folders.

[justinsalamon]

I need more information to be able to help resolve this issue. Please provide a minimal working example for the code that generated this error. Please also specify:

• Your source folder structure and contents (foreground and background)
• Scaper version, Python version, and operating system

Thanks