For those with the Line258 error like me, there has been an anwser from the devs on the official itch.io page in the comments but I've decided to paste it here for convenience:
"Hiya! I’m going to assume this is about the Line 258 Error?
We’ve generally seen this occur on systems with 1GB of VRAM. Due to the amount of Textures & Models within the game we can only support systems with 2GB+.
Version 0.3 still had some leeway with the amount of memory the game was using but with the update to 0.4 it seems like we’ve crossed that limit. Sadly we can’t really do anything about this.
If your system has more than 1GB of VRAM feel free to check into the Discord or shoot a mail to
contact@monsterbox.moe so we can investigate this further!"
In case you have 1GB or less VRAM, now you know the reason for the error.
I however use a 5700XT with 8GB VRAM so it shouldnt be an issue for me, yet it is. As stated in the message, if you have technical difficulties then feel free to help them troubleshoot it by contacting them on discord or through the e-mail provided.