[5.7] Fix assertSessionDoesntHaveErrors() when there is no errors

[shadoWalker89]

When the response has no errors at all and we do

$response->assertSessionDoesntHaveErrors('can_be_invited_as_reviewer');

A php error will occur
Error : Call to a member function getBag() on null F:\projects\quick-conference\src\quick-conference\vendor\laravel\framework\src\Illuminate\Foundation\Testing\TestResponse.php:904

The reason is that the assertion method is not taking into consideration someone checking that a specific error is missing when there is no errors at all.

Having this in a test

$response->assertSessionDoesntHaveErrors('can_be_invited_as_reviewer');

intead of this

$response->assertSessionDoesntHaveErrors();

makes it clearer that the test is checking that the can_be_invited_as_reviewer is missing.

Edit: btw the assertJsonMissingValidationErrors() allows for the behavior that the PR is adding, this will make things more consistent.

[taylorotwell]

Might be better to actually make an assertion? Even assertTrue(true) just so PHPUnit doesn't confusingly complain about no assertions being made in a test that only calls this method.

[shadoWalker89]

You are totally right. Change applied.