I'm so sorry to hear this, a quick google search claims that the error could come from the device. Have you tried using another one or another browser? Also, do other games in Godot webgl have the same error?
I ran into the same error on some other Godot WebGL games too so it might be that! The concept looks really good though so if I can find a PC or anything I'll try to come back and try this! :D
