For some reason on some sites with have a slide for which we can find the parent. As a result entering edit mode results in an error. This guards against this situation, although it should be noted that it's not a fix at all - we shouldn't ever be in this situation - just a chance to get a bit further.
Coverage decreased (-0.24%) to 84.44% when pulling d89ba63b0193393cb86bd699352b27f54a1b86c6 on slide-tyle-no-parent into 9a856bd99604d389102fdbfdb0306ca93102e524 on master.
For some reason on some sites with have a slide for which we can find the parent. As a result entering edit mode results in an error. This guards against this situation, although it should be noted that it's not a fix at all - we shouldn't ever be in this situation - just a chance to get a bit further.