I have a problem using full text search with q:<searchterm>. The response I get currently is 'TypeError: r is null'. I verified that the <searchterm> is part of a task.
Please let us know what's the search term you're referring to and what's the full task name as it may be important to identify this issue.
You can use any example if you can reliably reproduce it with a certain task on a certain browser (also let us know if this happens in at least 2 different browsers).
After you suggested to use different browsers I tested IE and Android and found no error. I then did logout/login on Firefox. This resolved the error.