Update src/main.py

src/main.py

@@ -289,6 +289,7 @@ def song_cover_pipeline(main_vocals, backup_vocals, voice_model, pitch_change, k
 
         if backup_vocals == "":
             print("####### ENTRATO QUA, BACKUP VOCALS NON DATI IN INPUT ########")
+            ai_vocals_mixed_path = convert_to_stereo(ai_vocals_mixed_path)
             return ai_vocals_mixed_path
             
         display_progress('[~] Combining AI Vocals and Instrumentals...', 0.9, is_webui, progress)