function checkShaderStatus(gl, shaderType, shader, errFn) {
  errFn = errFn || error;
  // Check the compile status
  var compiled = gl.getShaderParameter(shader, COMPILE_STATUS);
  if (!compiled) {
    // Something went wrong during compilation; get the error
    var lastError = gl.getShaderInfoLog(shader);
    var _prepShaderSource = prepShaderSource(gl.getShaderSource(shader)),
      lineOffset = _prepShaderSource.lineOffset,
      shaderSource = _prepShaderSource.shaderSource;
    var _error = "".concat(addLineNumbersWithError(shaderSource, lastError, lineOffset), "\nError compiling ").concat(utils.glEnumToString(gl, shaderType), ": ").concat(lastError);
    errFn(_error);
    return _error;
  }
  return '';
}
Check Shader status
@param {WebGLRenderingContext} gl The WebGLRenderingContext to use.
@param {number} shaderType The shader type
@param {WebGLShader} shader The shader
@param {ErrorCallback} [errFn] function to receive error message.
@return {string} errors or empty string
@private