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;

    errFn("".concat(addLineNumbersWithError(shaderSource, lastError, lineOffset), "\nError compiling ").concat(utils.glEnumToString(gl, shaderType), ": ").concat(lastError));
  }

  return compiled;
}
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 {bool} true if shader is ok.
@private