Thats what I was saying earlier, there is no way to get pass the php error notification unless your hosting company reverts you back to a previously saved point, or if you replace the functions.php file (where the error was made) with a working functions.php file (without the error, or the original file).
If it happened to me, I would simply login to filezilla (the FTP program I use) and look into the folders where my theme is located and delete or overwrite the functions.php file with one that doesn’t have the error. Although I personally never run into this issue because I always edit from FTP.
So you’ll definitely need to either have your hosting company revert you back to a saved point, or you would need to setup a FTP program. I recommend setting up a FTP program, it’s a faster more secure way of editing your files.