Blank homepage after Debian update

[GTP95]

I am running Firefly III version 4.8.1.4

Description
I was able to setup Firefly III and get to the point where I could reach the registration page via browser, but didn't registered any account yet. I left it as it was for some days, then four days ago I updated some packages on my Debian installation and checked the home page again, but this time I got a blank page. I'm quite sure that this is not caused by my Apache config (did some tests). In firefly's log folder I found two files, the one with the date of that day is called "ff3-apache2handler-2019-10-15.log" and contains the following error

[2019-10-15 13:05:22] local.ERROR: Class hash does not exist {"exception":"[object] (ReflectionException(code: -1): Class hash does not exist at /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Container/Container.php:788)
[stacktrace]
#0 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Container/Container.php(788): ReflectionClass->__construct('hash')
#1 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Container/Container.php(667): Illuminate\Container\Container->build('hash')
#2 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Container/Container.php(615): Illuminate\Container\Container->resolve('hash', Array)
#3 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Application.php(767): Illuminate\Container\Container->make('hash', Array)
#4 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Container/Container.php(1227): Illuminate\Foundation\Application->make('hash')
#5 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Auth/CreatesUserProviders.php(82): Illuminate\Container\Container->offsetGet('hash')
#6 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Auth/CreatesUserProviders.php(40): Illuminate\Auth\AuthManager->createEloquentProvider(Array)
#7 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Auth/AuthManager.php(123): Illuminate\Auth\AuthManager->createUserProvider('users')
#8 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Auth/AuthManager.php(94): Illuminate\Auth\AuthManager->createSessionDriver('web', Array)
#9 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Auth/AuthManager.php(68): Illuminate\Auth\AuthManager->resolve('web')
#10 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Auth/AuthManager.php(297): Illuminate\Auth\AuthManager->guard()
#11 /mnt/www/firefly-iii/app/Exceptions/Handler.php(132): Illuminate\Auth\AuthManager->__call('check', Array)
#12 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(314): FireflyIII\Exceptions\Handler->report(Object(ErrorException))
#13 /mnt/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(118): Illuminate\Foundation\Http\Kernel->reportException(Object(ErrorException))
#14 /mnt/www/firefly-iii/public/index.php(76): Illuminate\Foundation\Http\Kernel->handle(Object(Illuminate\Http\Request))
#15 {main}
"}

repeated a few times. If you need it here is a pastebin of the full log: https://pastebin.com/T2z8nzDu. My understanding is that I'm missing a library, but I don't know which one.
Thanks for your help.

Extra info
Although I think the Debian update s the most likely cause I can't be sure it was the update fault because:

1. I didn't check if it was working immidiately before the update
2. Due to my setup, the SBC that runs Firefly has suufered some power loss, I'm working to fix this.

Bonus points

[JC5]

Make sure your webserver is running PHP 7.3, and run composer install just in case. Is there still an .env file with a correct config?

[GTP95]

Thanks for your help. I have PHP 7.3.9 and the config in the .env file looks fine. I've ran composer install and during the Generating optimized autoload files" phase gave me the following error:

[RuntimeException]
Could not scan for classes inside "database/seeds" which does not appear to be a file nor a folder

After this I tried to connect to see if this solved the problem anyway and I got a 404 error. After some investigation I found out that I don't have the "public" folder inside "firefly-iii". I don't know if my Apache config was right, but previously I got it working bi setting the document root to /var/www/firefly-iii/public but this doesn't work anymore. Should I reinstall firefly or there is something else I should try?
EDIT: I'm thinking about downloading the public folder from this repo, do you think this could work?

[GTP95]

A quick try at retrieving the "public" folder from this repo didn't work. Since there is a new release of Firefly-III, I'm reinstalling now to fix the problem and get the new version at the same time.