To add a race to the game you will need a beginner level understanding of programming and be familiar with GDScript's syntax. The races.gd file uses a fairly simple syntax for someone familiar with coding, but even a single wrong white-space, comma, parenthesis, or bracket will break the entire file. If you used the Microsoft Notepad that comes default with the OS, then that program likely caused the crash as it does not handle newlines in the same way as the game. Any decent text editor can be used, but most people use one of these three programs: the Godot editor, Notepad++, or Sublime Text 3.

The debug mod (https://itch.io/t/1137280/debugmod-v1) is quite useful for modding as it gives faster feedback, but without experience with coding and debugging it may be quite difficult to utilize. The Discord(https://itch.io/t/284398/discord) is a good place to ask for help but adding new races is a tedious task, which is why there are almost no mods that add new races. 

races.gd handles only between one third to one half of the code relevant to adding a new race. Strive does not centralize concepts well, so you will probably need to edit a minimum of 4 other files, but it could be more depending on the racial ability. The number and type of edits you would need to make depend heavily on how similar or different the race is to existing races.