Calls to SentryTracingBuilder can now be chained correctly

[jamescrosswell]

Resolves #2721

Problem

The dotnet UseRouting and UseEndpoints methods are just extensions on the builder... they set properties etc. on the builder before adding middleware. The only part of what they do that gets passed to the SentryTracingBuilder.InnerBuilder then is the delegate that they return on the last line of their implementation (e.g. this).

Previously we were calling that delegate against the InnerBuilder and returning the result directly (which implicitly returns a reference to the InnerBuilder). Chained calls would then be against the InnerBuilder rather than the SentryTracingBuilder.

This caused issues since UseRouting sets properties on the SentryTracingBuilder and then (in the chained call) UserEndpoints tries to follow up with some matching logic... only it's not using the same builder! It's using the InnerBuilder at this stage 😢

Solution

We've separated using the InnerBuilder to call the delegate from the return value in our SentryTracingBuilder so that for chained calls, the same builder will always be used.

[bitsandfoxes]

🔥