Update ultravox_processing.py

ultravox_processing.py

@@ -165,7 +165,7 @@ class UltravoxProcessor(transformers.ProcessorMixin):
             #), "Text must be a string. Batch mode not supported yet."
             data["audio_token_start_idx"] = []
             for t in text:
-                assert self.audio_placeholder in t
+                assert self.audio_placeholder in t, f"audio must be provided when using audio placeholder ({self.audio_placeholder}) in text: {t=}."
                 if "audio_token_len" not in data:
                     raise ValueError(
                         f"audio must be provided when using audio placeholder ({self.audio_placeholder}) in text."