handle json parsing error for empty return body

a 404 message can be returned from the server without having a message in it (when deleting from an index with key, value and id and an empty string is contained in the value)

lib/neography/connection.rb

@@ -105,9 +105,15 @@ def evaluate_response(response)
     end
 
     def handle_4xx_500_response(code, body)
-      parsed_body = JSON.parse(body)
-      message = parsed_body["message"]
-      stacktrace = parsed_body["stacktrace"]
+      if body
+        parsed_body = JSON.parse(body)
+        message = parsed_body["message"]
+        stacktrace = parsed_body["stacktrace"]
+      else
+        parsed_body = {}
+        message = "No error message returned from server."
+        stacktrace = ""
+      end
 
       @logger.error "#{code} error: #{body}" if @log_enabled
 

spec/integration/rest_index_spec.rb

@@ -167,6 +167,16 @@
       new_index = @neo.get_relationship_index("test_relationship_index", key, value) 
       new_index.should be_nil
     end
+
+    it "throws an error when there is an empty string in the value when removing a node" do
+      new_node = @neo.create_node
+      key = generate_text(6)
+      value = generate_text
+      @neo.add_node_to_index("test_node_index", key, value, new_node) 
+      new_index = @neo.get_node_index("test_node_index", key, value) 
+      new_index.should_not be_nil
+      expect { @neo.remove_node_from_index("test_node_index", key, "", new_node) }.to raise_error
+    end
   end
 
   describe "get index" do