Blender Git Loki

[#25278] Ctrl-left click in beizer edit mode with no selection results
in crash.

This commit fixes the crash (missing null check for nu==NULL).

However, there is still a problem here with Curve Ctrl-Click not
behaving the same as Mesh EditMode Ctrl-Click, which adds a new vert
no matter what (i.e. no previous selection required). Then again,
that's a separate "todo" issue, so we can close this report now :)