Exception thrown in AuthorizeDirectiveType due to no default constructor in AuthorizeDirective

[michaelmccord]

Describe the bug
Due to the behavior of Directive.ToObject, AuthorizeDirectiveType throws an exception in AuthorizeAsync on this line:

AuthorizeDirective directive = context.Directive
                .ToObject<AuthorizeDirective>();

The exception is thrown due to the use of Activator.CreateInstance where AuthorizeDirective has no default constructor and no constructor arguments are provided to Activator.CreateInstance. This circumstance seems to be the result of choices made around the "implicit" arguments model which seem to imply (at least currently...assuming I understand correctly) that a directive must have a default constructor.

To Reproduce
Steps to reproduce the behavior:

1. Add the @authorize directive to a schema
2. Register the directive
3. Query the field or type which is protected by the directive
4. Note that an exception is thrown and processing continues as normal (the fact that processing continues as normal seems to be an issue as well, I would have expected that an error be returned for this too, separate bug?)

Expected behavior

1. When an exception is thrown in the GraphQL middleware pipeline, I would expect to see an error response noting this.
2. The use of the @authorize directive should not throw an exception in the GraphQL pipeline

Desktop (please complete the following information):

• OS: Windows 10
• Version:10.0.17134.0

Additional context
N/A

[michaelmccord]

Pull Request: #441 created to resolve this issue.

[michaelstaib]

Note that an exception is thrown and processing continues as normal (the fact that processing continues as normal seems to be an issue as well, I would have expected that an error be returned for this too, separate bug?)

I will write a test for this one.

[michaelstaib]

This one is now fixed with #485 and will be included in 0.7.0-preview.31.