I decided to piddle around and explore adding new areas, because who doesn't like exploring more places? Well I was immediately unsuccessful and I'm not quite sure where/what my problem is exactly.  So here's the steps I took (according to the modding guide and in the posts I've read here):

Step 1: Create /mods folder in User/AppData/Roaming/Strive/mods

Step 2: Create folder in /mods, eg: User/AppData/Roaming/Strive/mods/Expanded/scripts

Step 3: Identify GD files for existing areas (ignoring ones that seemed quest/teleport related)-- explorationregions.gd and gallery.gd

Step 4: Copy existing area (Marsh in this case) and tweak it. 'Marsh Ruin' created, exit to new 'Marsh Ruin' added to 'Marsh', exit FROM 'Marsh Ruin' set to 'Marsh'. Slightly tweak enemy list.-----Saved and added explorationregions.gd to /mods/Expanded/scripts

Step 5: Same as the above (just setting a background picture in gallery.gd)---- Saved and added gallery.gd to /mods/Expanded/scripts

Step 6: Open Strive.exe, click mod(s) on main menu. Click mod, click apply, crash game.

Where did I lose the wheels on my short bus? See attached picture. (https://imgoat.com/v/144578/crashycrash) I barely caught the console errors via screenshot before everything exited out (hence the fading). The bottom of the pic is the explorationregions.gd, the top right is gallery.gd, and the top left is the console errors thrown.

Can someone more educated/knowledgeable than me, point out where I went wrong/spilled the teapot?

Thanks

You don't really need a marshruin background if you are not using it in area data. Also it's quite hard to say what went wrong without your code. 

https://pastebin.com/VUqB57eq

https://pastebin.com/ZtXcEgxM

explorationregions.gd and gallery.gd pastebins respectively. I know the background isn't really needed but I figured I play around with it anyway.  I assume the problem I've having is that any new additions actually need to be 'called out' I guess? And not just 'inserted' in to existing code.

Edit: @ Line 117 on explorationregions.gd

@ Line 506 gallery.gd

Just tried using it without gallery with no issue. I suggest trying to remove it and try again. Also what is your OS?

Clicking apply exits the game, it's normal for it to exit when you apply a mod. It didn't "crash".  I do believe it'd be nicer if the game gave a message box at the end like "Mods applied successfully, please restart the game, exiting..." and an ok button.

The yellow bits in your screenshot happen every time you exit the game, applying a mod or not. The other errors are it looking for a info.txt file, add that to your mod folder and they go away.

You appear to be trying to wholesale replace the files, are you using version 0.5.19b? Older versions wouldn't handle correctly replacing a multi-line variable.  However, honestly, I don't like this approach. Doesn't work well if say you wanted your mod to play nice with someone else's mod. Instead I'd do it like this:

https://pastebin.com/SCDggsDh

This works, at least with 0.5.19b, but probably with most older versions too since it only adds a simple var and modifies a function.  It works in a manner that would play nice with other mods.  You could have 20 mods like this, each adding their own regions, and as long as they named them something different, they'd all work.