fix: retrieve mm token by modality, raise error if none (#8221)

Signed-off-by: Xinyuan Tong <xinyuantong.cs@gmail.com>
Co-authored-by: Xinyuan Tong <xinyuantong.cs@gmail.com>

python/sglang/srt/multimodal/processors/base_processor.py

@@ -101,6 +101,14 @@ class MultimodalSpecialTokens:
 
         return None
 
+    def get_token_id_by_modality(self, modality: Modality) -> Optional[int]:
+        return {
+            Modality.IMAGE: self.image_token_id,
+            Modality.MULTI_IMAGES: self.image_token_id,
+            Modality.VIDEO: self.video_token_id,
+            Modality.AUDIO: self.audio_token_id,
+        }.get(modality)
+
     def parse_regex(self):
         if self.image_token_regex is None and self.image_token is not None:
             self.image_token_regex = re.compile(re.escape(self.image_token))
@@ -608,14 +616,12 @@ class BaseMultimodalProcessor(ABC):
 
         # Add offsets to all items
         for mm_item in all_collected_items:
+            mm_token_id = mm_tokens.get_token_id_by_modality(mm_item.modality)
+            if mm_token_id is None:
+                raise ValueError(f"No token id found for modality: {mm_item.modality}")
             mm_item.offsets = self.get_mm_items_offset(
                 input_ids=input_ids,
-                mm_token_id={
-                    Modality.IMAGE: mm_tokens.image_token_id,
-                    Modality.MULTI_IMAGES: mm_tokens.image_token_id,
-                    Modality.VIDEO: mm_tokens.video_token_id,
-                    Modality.AUDIO: mm_tokens.audio_token_id,
-                }.get(mm_item.modality, None),
+                mm_token_id=mm_token_id,
             )
 
         return all_collected_items, input_ids, ret