[Solved] Laravel 5.8 - php artisan package:discover handling the post-autoload-dump event returned with error code 1

I installed and updated the packages of Laravel 5.8 ( PHP v7.4.33). However I could not install packages, and this is an error message.

Could not install packages or Could not update packages

Installing application packages
Installing dependencies from lock file
Verifying lock file contents can be installed on current platform.
Nothing to install, update or remove
.
.
.
Package phpunit/phpunit-mock-objects is abandoned, you should avoid using it. No replacement was suggested.
Generating optimized autoload files
> Illuminate\Foundation\ComposerScripts::postAutoloadDump
> @php artisan package:discover
Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1
In Collection.php line 2073:
Undefined offset: 0

Above error, I could not analyze. So I delete some files to check the problem. By focusing on :

Undefined offset: 0`

The "Undefined offset" notice is given when you try to access an array element with an invalid index, that is, the index is outside the bounds of the array.

After so much spending time. Finally, I have found the problem file. (/app/Providers/AppServiceProvider.php)

I forgot to check the value in the array! , And this is the main cause of these issues. So I added the checking of this array to my code and used composer install and update again.

How to avoid PHP Notice "Undefined offset: 0".

if(isset($array[0])){
    echo $array[0];
} else {
   echo 'no data';
}

# or 

echo $array[0] ?? 'no data';

Enjoy with coding ❤️