Applying templates to ships in modular tables creates hard crash on mission launch

So I largely expected this to not work, but I expected it to complain on game load, not mission. If you have a ship that is previously defined, then create a template, and in a TBM apply the template, the game crashes.

Attached is a repro that works for retail.
[wm-TF-FS2-shp.zip](https://github.com/scp-fs2open/fs2open.github.com/files/6721092/wm-TF-FS2-shp.zip)

Why I was trying to do this was to make a template for Warmachine that contains all the various tweaks we want to use, glide, banking constant, armor types, energy transfer removal... and just 'stamp' that over all the ships we get from the retail, mvp, and bp tables. I won't complain if the fix to this bug is just to have table loading throw a fit earlier, but that's what I be able to do in my perfect world.