laravel 5.x and php 7.0 update to 7.4 bug

LARAVEL 5.X AND PHP 7.0 UPDATE TO 7.4 BUG

or

Change Your Php version in Composer.json to 7.4.1 and run

composer update

In line 147 of this file vendor\egulias\email-validator\EmailValidator\Parser\Parser.php

Change it from this if ($previous['type'] === EmailLexer::S_BACKSLASH

To this if (isset($previous['type']) && $previous['type'] === EmailLexer::S_BACKSLASH