[Bugfix] Fix Mistral ChatCompletionRequest Body Exception (#16769)

Signed-off-by: Jasmond Loh <Jasmond.Loh@hotmail.com>
Co-authored-by: Cyrus Leung <cyrus.tl.leung@gmail.com>

vllm/entrypoints/chat_utils.py

@@ -1198,6 +1198,8 @@ def apply_hf_chat_template(
             "allowed, so you must provide a chat template if the tokenizer "
             "does not define one.")
 
+    try:
+
         return tokenizer.apply_chat_template(
             conversation=conversation,  # type: ignore[arg-type]
             tools=tools,  # type: ignore[arg-type]
@@ -1206,6 +1208,15 @@ def apply_hf_chat_template(
             **kwargs,
         )
 
+    # External library exceptions can sometimes occur despite the framework's
+    # internal exception management capabilities.
+    except Exception as e:
+
+        # Log and report any library-related exceptions for further
+        # investigation.
+        logger.exception(
+            "An error occurred in `transformers` while applying chat template")
+        raise ValueError from e
 
 def apply_mistral_chat_template(
     tokenizer: MistralTokenizer,
@@ -1214,6 +1225,8 @@ def apply_mistral_chat_template(
     tools: Optional[list[dict[str, Any]]],
     **kwargs: Any,
 ) -> list[int]:
+    from mistral_common.exceptions import MistralCommonException
+
     # The return value of resolve_mistral_chat_template is always None,
     # and we won't use it.
     resolve_mistral_chat_template(
@@ -1231,5 +1244,16 @@ def apply_mistral_chat_template(
     # if input does not comply with the expected format.
     # We convert those assertion errors to ValueErrors so they can be
     # are properly caught in the preprocessing_input step
-    except AssertionError as e:
+    except (AssertionError, MistralCommonException) as e:
+        raise ValueError from e
+
+    # External library exceptions can sometimes occur despite the framework's
+    # internal exception management capabilities.
+    except Exception as e:
+
+        # Log and report any library-related exceptions for further
+        # investigation.
+        logger.exception(
+            "An error occurred in `mistral_common` while applying chat "
+            "template")
         raise ValueError from e