I recently downloaded the game and it opens just fine, but once it's running it gives me a black screen that stays for a minute or so. And then text shows up saying that the game's failed to execute "attachShader" on "WebGLRenderingContext".

How do I circumvent this issue?

The problem is that WebGL may not support your version of WebGL Support. The solution is that you may have to go to https://get.webgl.org/ to test your WebGL Shaders. If it says that it works and your restart the game with the same error, It may be the operating system your running. If that's not the problem, contact WebGL for further help.