function isError( value ) {
	if ( typeof value !== 'object' || value === null ) {
		return false;
	}
	// Check for `Error` objects from the same realm (same Node.js `vm` or same `Window` object)...
	if ( value instanceof Error ) {
		return true;
	}
	// Walk the prototype tree until we find an object having the desired native class...
	while ( value ) {
		if ( nativeClass( value ) === '[object Error]' ) {
			return true;
		}
		value = getPrototypeOf( value );
	}
	return false;
}
Tests if a value is an `Error` object.

@param {*} value - value to test
@returns {boolean} boolean indicating whether a value is an `Error` object

@example
var bool = isError( new Error( 'beep' ) );
// returns true

@example
var bool = isError( {} );
// returns false