Hey, sorry about that! The first error you posted is expected for the itch build and not indicative of any real error state.
The second error is definitely something internal to Godot that I as a solo dev don't have the resources to debug. The internet suggests that some Linux systems may have an issue with Godot's default Vulkan driver, so the first thing I would try is running the program with the following command line argument:
--rendering-method gl_compatibility
This may fix the crash issue. If it does not, I can issue you a refund.
Again, sorry for the inconvenience.
-gate