I don't fully understand your report, first you say the error happens when starting pushback, then you said there's a problem in the editor selecting the wrong starting object. Are you getting the error there, or you are just reporting two entirely different things ?
Because, the editor is really a minor issue, and won't affect pushback as such, the only effect is your would need to cycle on the next editable object.
So, assuming you really wanted to report to entirely unrelated issues, from your error log, I can first tell you don't have the latest version, because the error points to a line of code that has been moved in the current version.
However, that doesn't mean updating will surely fix that, because from what the error says, it seems you got a completely faulty pushback, but that's can be caused by either a problem on a particular pushback on a particular airport, or by the airplane configuration itself.
Of course, had you provided more information, like if it happens only on a specific airport or pushback procedure (default Left/Right, edited, Quickedit) or if it happens everywhere, I might be able to say more but basically, the meaning of the error is that pushback stopped immediately even before the airplane started to move, which of course is not normal
