I'm trying to do an advanced search in JIRA where the assignee was the reporter.
assignee = reporter doesn't work, it throws this error: The value 'reporter' does not exist for the field 'assignee'.
I'm able to do assignee = currentuser() and reporter = currentuser() without issue but of course that doesn't return what I want.
This cannot be done using JQL. You basically have two option: write a script that performs this search, or use a plugin which enables you to do advanced searches and reports.
The one I use is the (non-free) ScriptRunner plug-in that provides many powerful capabilities, including advanced search functions. For example, to search for all issues where the assignee is also the reporter, write this in the JQL query:
issuefunction in expression("project = FOO", "assignee == reporter")
