It didn't crash anymore, but the addon didn't load either.
So I found out I had to enable the bot_hole for the playertype to work.
Then I saw the bot_spongebob addon didn't forceload the bot_hole, but instead used its own version for some reason.
It used this code:
if(LoadRequiredAddOn("Bot_Hole") == $Error::None)
exec("./bot_base.cs");
After I changed this to my code, it does work.
Yet it still gives the error: "Bot_Spongebob - required add-on not found".
Well, it is something weird. But as long as everything is loaded correctly, I don't mind.