Compile errors are returned with gl.getShaderParameter(shader, gl.COMPILE_STATUS), Link errors are returned with gl.getProgramParameter(program, gl.LINK_STATUS)Neither of those are actually an error.Also, you can compile X shaders and link Y programs all without checking the status of any of them. Which effectively means you can async compile multiple things at once. If you wanted to check them you'd need to able to check them individually, not with something like getLastError. Which one would be get getting the error for?
But, back to the original point. I'm still not sure this is a priority.