ErrorException : Return value of "Illuminate\Foundation\Console\PackageDiscoverCommand::execute()" should always be of the type int since Symfony 4.4, NULL returned

This issue Laravel 6.* installation getting failing because PHP Error Suppress operator (@) is disabled in PHP configuration file using following directive.

scream.enabled=1;

#or 

xdebug.scream =1;

This scream directive will disable the effects of error suppression operator (@).

So please disable the following directive in your php.ini file.

scream.enabled=0;

#or 

xdebug.scream =0;