fixed NaN in json exports

api.py

@@ -122,9 +122,12 @@ def validator():
     model_data = state_vars["model_data"]
     validator_df = state_vars["validator_df"]       
 
-    return jsonify(
-        utils.make_validator_dataframe(validator_df, model_data).to_dict(orient='records')
-        )
+    validator_df = utils.make_validator_dataframe(validator_df, model_data)
+    json_data = [ row.dropna().to_dict()
+                  for _, row in validator_df.iterrows() ]
+
+    return jsonify(json_data)
+
 
 @app.route('/model-data', methods=['GET'])
 def model_data():