Synchronize on something more sensible.

Change-Id: I3b0d649a3a545e5747b8e2531d47f2d11bfef171
Reviewed-on: http://gerrit.dmdirc.com/3978
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <chris@dmdirc.com>
Fix an unguarded read in ErrorTableModel.

Change-Id: Ifcb309ce73ebed15dc17cadc6beddd261527bca9
Reviewed-on: http://gerrit.dmdirc.com/3979
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <chris@dmdirc.com>