Better error messages for incorrectly encoded xmlquery

[ato]

/trove?q=type:urlquery+url:http://www.tisn.gov.au/Documents/CIPMA+tasking+application+form.doc unhelpfully returns java.lang.ArrayIndexOutOfBoundsException

(The problem is that the value of the url field needs to url-encoded twice. Once for the query string and once for opensearch.)