Allow for response errors to be passed back from a plugin

[briankassouf]

Plugins were previously swallowing the response errors when an error was also returned:

return logical.ErrorResponse("..."), logical.ErrInvalidRequest

[calvn]

Should the same be applied for HandleExistenceCheck()?

[jefferai]

^ that -- other than that looks good. Although keep in mind that this may need to be applied to the persona lookahead once that is on this side of things, so you may want to do that as a followup on the other side so it doesn't get lost.

[briankassouf]

@jefferai @calvn I believe HandleExistenceCheck is already handling this correctly. Jeff, I'll make a PR for the persona lookahead version.

[calvn]

Yea, you're right. Since HandleExistenceCheck doesn't return reply.Response, return false, false, reply.Error should be fine since those would be reply.CheckFound and reply.Exists zero values.

[calvn]

The tests are showing that it's returning <nil> string instead of a nil object.

[calvn]

I think you might need to do return reply.Response, reply.Error here, and keep the other line to explicitly return nil

[briankassouf]

@calvn updated, and I tested with the the kubernetes plugin

[calvn]

Yep, LGTM!