Check for :raise_errors config before calling it

[jeffkreeftmeijer]

Rack middleware doesn't usually include a #settings method, so we can't
rely on it existing in Appsignal::SinatraBaseInstrumentation.

[tombruijn]

This happens when another middleware is loaded before appsignal's middleware, right?

In this scenario you would lose the setting raise_errors if it's set on the application, because you're asking the middleware.

---

But don't middleware wrap each other? So can we call up, find the original application and ask it its settings?

some_app = @app
while !some_app.is_a? Sinatra::Base
  some_app = some_app.instance_variable_get(:@app)
end

but that's of course pretty terrible and brittle. We can't ask ::Sinatra::Application.settings either, because that only works for non-modular apps.

So... ¯_(ツ)_/¯ ?

---

Your solution will not crash the application anymore 👍 , but does seem to break the config.

[jeffkreeftmeijer]

Agreed. As middleware is stacked, we should be able to call the "main" app for its config. However, the while loop looks a little too scary for me, do I think we should take a bit more time to get to a solution that's more stable.

Without this patch, every Sinatra app with middleware that doesn't have a #settings method won't start. With this patch, it will, but it can lose the config in the middleware. I propose we create a new issue to look into it some more, but merging this and pushing a gem update so apps like this can at least start. wdyt? :)

[tombruijn]

Applying this patch 👍
Creating a new issue 👍