Fix repr

Author: samruds

src/sagemaker/serve/builder/schema_builder.py

@@ -208,13 +208,14 @@ def _get_inverse(self, obj):
 
     def __repr__(self):
         """Placeholder docstring"""
-        return (
-            f"SchemaBuilder(\n"
-            f"input_serializer={self.input_serializer}\n"
-            f"output_serializer={self.output_serializer}\n"
-            f"input_deserializer={self.input_deserializer._deserializer}\n"
-            f"output_deserializer={self.output_deserializer._deserializer})"
-        )
+        if hasattr(self, "input_serializer") and hasattr(self, "output_serializer"):
+            return (
+                f"SchemaBuilder(\n"
+                f"input_serializer={self.input_serializer}\n"
+                f"output_serializer={self.output_serializer}\n"
+                f"input_deserializer={self.input_deserializer._deserializer}\n"
+                f"output_deserializer={self.output_deserializer._deserializer})"
+            )
 
     def generate_marshalling_map(self) -> dict:
         """Generate marshalling map for the schema builder"""