Fix ambiguity issue with numpy artifact retrieval

Author: kzscisoft

simvue/client.py

@@ -641,7 +641,9 @@ def get_artifact(
             response.content, mimetype, allow_pickle
         )
 
-        return content or response.content
+        # Numpy array return means just 'if content' will be ambiguous
+        # so must explicitly check if None
+        return response.content if content is None else content
 
     @prettify_pydantic
     @pydantic.validate_call