[Bugfix] support tie_word_embeddings for all models (#5724)

vllm/model_executor/models/commandr.py

@@ -321,6 +321,9 @@ class CohereForCausalLM(nn.Module):
     ) -> None:
         super().__init__()
         self.config = config
+        # currently all existing command R models have `tie_word_embeddings`
+        # enabled
+        assert config.tie_word_embeddings
         self.unpadded_vocab_size = config.vocab_size
         if lora_config:
             self.unpadded_vocab_size += lora_config.lora_extra_vocab_size