### Compilation failed:

error: 1: 'main' must return: 'vec4', 'float4', or 'half4'
void main() {
^^^^^^^^^^^
error: 5: discard statement is only permitted in fragment shaders
       default: x = 1; discard;
                       ^^^^^^^
error: 7: unknown identifier 'sk_FragColor'
    sk_FragColor = half4(x);
    ^^^^^^^^^^^^
3 errors