Steps:
1. Login to JIRA
2. Try to run a query like summary ~ and or try to use any of the reserved words from the list.

Result:
1. User get message "Unable to parse the query 'summary ~ and' with thrown exception: 'An error occured while parsing the JQL 'summary ~ and'.'."
2. The message help user least and will take some time to figure out what exactly is issue.

Expected:
1. A proper error message explaining that reserved words should be used within quotes or explaining that you can't use reserved words without quotes.