[Core] More fixes to MultiModalEmbeddings type handling (#19715)

Signed-off-by: Russell Bryant <rbryant@redhat.com>

vllm/model_executor/models/kimi_vl.py

@@ -393,7 +393,8 @@ class KimiVLForConditionalGeneration(nn.Module, SupportsMultiModal):
         # model as one of the requirements of basic vLLM model implementation.
         inputs_embeds = self.language_model.get_input_embeddings(input_ids)
 
-        if multimodal_embeddings is not None:
+        if multimodal_embeddings is not None and len(
+                multimodal_embeddings) != 0:
             inputs_embeds = merge_multimodal_embeddings(
                 input_ids=input_ids,
                 inputs_embeds=inputs_embeds,