function isError(value) {
      return (value && typeof value == 'object' && toString.call(value) == errorClass) || false;
    }
Checks if `value` is an `Error`, `EvalError`, `RangeError`, `ReferenceError`,
`SyntaxError`, `TypeError`, or `URIError` object.

@static
@memberOf _
@category Lang
@param {*} value The value to check.
@returns {boolean} Returns `true` if `value` is an error object, else `false`.
@example

_.isError(new Error);
// => true

_.isError(Error);
// => false