Fix memory leaks

Summary:
Fix a few memory leaks, and some other minor fixes
Before:
{F5831175}
After:
{F5831176}

Reviewers: rkflx

Reviewed By: rkflx

Subscribers: anthonyfieroni, ngraham, rkflx, #spectacle

Tags: #spectacle

Differential Revision: https://phabricator.kde.org/D12671