WordPress Appearance error

How do i stop this error? i want to ignore this stupid error, or undo wordpress version, i was never uncomfortable with wordpress until this version creating this error while editing my wordpress theme in “Editor”.

Also, i don’t want to use SFTP or FTP so tell me a solution to fix this normally

Unable to communicate back with site to check for fatal errors, so the PHP change was reverted. You will need to upload your PHP file change by some other means, such as by using SFTP.