Update src/main.py

src/main.py

@@ -286,6 +286,10 @@ def song_cover_pipeline(main_vocals, backup_vocals, voice_model, pitch_change, k
             display_progress('[~] Applying overall pitch change', 0.85, is_webui, progress)
             backup_vocals = pitch_shift(backup_vocals, pitch_change_all)
 
+        if backup_vocals == "":
+            print("####### ENTRATO QUA, BACKUP VOCALS NON DATI IN INPUT ########")
+            return ai_vocals_mixed_path
+            
         display_progress('[~] Combining AI Vocals and Instrumentals...', 0.9, is_webui, progress)
         combine_audio([ai_vocals_mixed_path, backup_vocals], ai_cover_path, main_gain, backup_gain, inst_gain, output_format)