Weird "ÿÿÿÿ" Issue

lumen.log

[2016-03-15 14:02:41] lumen.ERROR: Symfony\Component\Debug\Exception\FatalErrorException: Uncaught Error: Class 'Symfony\Component\Debug\ExceptionHandlerÿÿÿÿ' not found in /home/vagrant/Projects/Atlantic/fluxx/vendor/laravel/lumen-framework/src/Exceptions/Handler.php:89
Stack trace:
#0 /home/vagrant/Projects/Atlantic/fluxx/app/Exceptions/Handler.php(48): Laravel\Lumen\Exceptions\Handler->render(Object(Illuminate\Http\Request), Object(Symfony\Component\Debug\Exception\FatalThrowableError))
#1 /home/vagrant/Projects/Atlantic/fluxx/vendor/laravel/lumen-framework/src/Concerns/RegistersExceptionHandlers.php(128): App\Exceptions\Handler->render(Object(Illuminate\Http\Request), Object(Symfony\Component\Debug\Exception\FatalThrowableError))
#2 /home/vagrant/Projects/Atlantic/fluxx/vendor/laravel/lumen-framework/src/Concerns/RegistersExceptionHandlers.php(51): Laravel\Lumen\Application->handleUncaughtException(Object(Symfony\Component\Debug\Exception\FatalThrowableError))
#3 [internal function]: Laravel\Lumen\Application->Laravel\Lumen\Concerns\{closure}(Object(Error))
#4 {main}
  thrown in /home/vagrant/Projects/Atlantic/fluxx/vendor/laravel/lumen-framework/src/Exceptions/Handler.php:89
Stack trace:
#0 /home/vagrant/Projects/Atlantic/fluxx/vendor/laravel/lumen-framework/src/Concerns/RegistersExceptionHandlers.php(55): Laravel\Lumen\Application->handleShutdown()
#1 [internal function]: Laravel\Lumen\Application->Laravel\Lumen\Concerns\{closure}()
#2 {main}

routes.php

<?php

use Illuminate\Http\Request;

$app->post('process/imports', function(Request $request) {
    // Having this errors :/
    (new App\FluxxImporter)->import([
        'starting_page' => $request->input('starting_page'),
        'ending_page'   => $request->input('ending_page')
    ]);

    return redirect('importing');
});

Reran composer dump-autoload, totally newly provisioned vagrant box, 0.4.2, on Lumen 5.2.

Craziest error.