Steps to reproduce

1. Open jira.atlassian.com and open your developer tools / firebug
2. Run the following JQL

   project = JRA AND status != Open

3. Although the results returns correctly, the following error appears in the developer tools
   

This error is triggered by the following JQL parameter: "WAS", "WAS NOT", "!=", "Changed"

there is no actual functionality broken in JIRA and search filter should returned correct result