Check if file exists on FilesystemStorage

[erikn69]

• Closes Debugbar exception: File does not exist at path #1758

This bug prevents the debugbar from being displayed, it can only be seen from the log file

Debugbar exception: File does not exist at path /var/www/storage/debugbar/976f3e1e7548.json. 

#0 /var/www/vendor/barryvdh/laravel-debugbar/src/Storage/FilesystemStorage.php(84):
    Illuminate\Filesystem\Filesystem->get('/var/www/storag...')
#1 /var/www/vendor/php-debugbar/php-debugbar/src/DebugBar/DebugBar.php(383):
    Barryvdh\Debugbar\Storage\FilesystemStorage->get('976f3e1e7548')
#2 /var/www/vendor/barryvdh/laravel-debugbar/src/LaravelDebugbar.php(1118):
    DebugBar\DebugBar->getStackedData(false)
#3 /var/www/vendor/barryvdh/laravel-debugbar/src/LaravelDebugbar.php(1107):
    Barryvdh\Debugbar\LaravelDebugbar->getStackedData(false)

Complement of php-debugbar/php-debugbar#777

[barryvdh]

Not sure why this would happen?

[erikn69]

Very specific cases, where something fails in a redirection, or if there are multiple calls and a profiles clear is executed, or if a stacked session remains, and some type of deletion is made to the files