View scheduled and View Sent Messages options results in dmlreadexception error

[ThomasITS]

I'm re-reporting this here incase LSU ITS isn't supporting any more. The View Scheduled and View Sent Messages options returns a dmlreadexception error. This was experienced in Moodle 3.7.2 and Quickmail v2.2.0. I've attached the full error and stack trace experienced for both. This pull request did not seem to fix the issue for us: lsuits/lsu-block_quickmail#289. Thanks.