fix: don't try to validate non-bytes as Path (#4765)

* fix: don't try to validate non-bytes as Path
Fix #4728

Signed-off-by: Frost Ming <me@frostming.com>

* fix: order

Signed-off-by: Frost Ming <me@frostming.com>

---------

Signed-off-by: Frost Ming <me@frostming.com>

Author: frostming

src/_bentoml_sdk/validators.py

@@ -143,9 +143,13 @@ def decode(self, obj: bytes | t.BinaryIO | UploadFile | PurePath | str) -> t.Any
                 if (fn := getattr(obj, "name", None)) is not None
                 else None
             )
-        else:
-            body = t.cast(bytes, obj)
+        elif isinstance(obj, bytes):
+            body = obj
             filename = None
+        else:
+            from pydantic_core import PydanticCustomError
+
+            raise PydanticCustomError("path_type", "Invalid file type")
         if media_type is not None and self.content_type is not None:
             if not fnmatch.fnmatch(media_type, self.content_type):
                 raise ValueError(