'Quick Filters' - JQL error during quick filter creation is not correctly handled on GUI

In the Rapid board quick filters tab, when user tries to create a 'Quick Filter' with invalid JQL, GUI do not provides correct error response.

Example of bad JQL (version is nonexisting field): version = '5.0.0.Alpha1'

When I try to create filter with this bad JQL (I click Add button), the ajax spinner spins forever. Error response received from the server is not reflected on GUI, no any error message is shown, which confuses users (see https://issues.jboss.org/browse/ORG-1633).

Response from the server is:

POST https://issues.jboss.org/rest/greenhopper/1.0/quickfilters/331/ 400 (Bad Request) 

Thanks for patch for this GUI issue.