anchor: love.graphics.validateShader
  Validates shader code. Check if specified shader code does not contain any errors.
  status, message = love.graphics.validateShader( gles, code )
  gles boolean Validate code as GLSL ES shader.
  code string The pixel shader or vertex shader code, or a filename pointing to a file with the code.
  status boolean true if specified shader code doesn't contain any errors. false otherwise.
  message string Reason why shader code validation failed (or nil if validation succeded).
  status, message = love.graphics.validateShader( gles, pixelcode, vertexcode )
  gles boolean Validate code as GLSL ES shader.
  pixelcode string The pixel shader code, or a filename pointing to a file with the code.
  vertexcode string The vertex shader code, or a filename pointing to a file with the code.
  status boolean true if specified shader code doesn't contain any errors. false otherwise.
  message string Reason why shader code validation failed (or nil if validation succeded).