RescuedExceptionInterceptor: Handle empty configuration

Previously, it could happen that `Sentry.configuration` was `nil`.
In this case, calling `rails` would produce a `NoMethodError`.
We fix this issue by using safe navigation.

Furthermore, this commit ensures we use a reasonable default
in case the configuration couldn't be loaded. Since the config
`report_rescued_exceptions` defaults to `true`, we assume
this value here, too.

Fixes #2386

CHANGELOG.md

@@ -7,6 +7,7 @@
 ### Bug Fixes
 
 - Fix Vernier profiler not stopping when already stopped [#2429](https://github.com/getsentry/sentry-ruby/pull/2429)
+- Fix `RescuedExceptionInterceptor` to handle an empty configuration [#2428](https://github.com/getsentry/sentry-ruby/pull/2428)
 
 ## 5.21.0
 

sentry-rails/lib/sentry/rails/rescued_exception_interceptor.rb

@@ -19,7 +19,16 @@ def call(env)
       end
 
       def report_rescued_exceptions?
-        Sentry.configuration.rails.report_rescued_exceptions
+        # In rare edge cases, `Sentry.configuration` might be `nil` here.
+        # Hence, we use a safe navigation and fallback to a reasonable default
+        # of `true` in case the configuration couldn't be loaded.
+        # See https://github.com/getsentry/sentry-ruby/issues/2386
+        report_rescued_exceptions = Sentry.configuration&.rails&.report_rescued_exceptions
+        return report_rescued_exceptions unless report_rescued_exceptions.nil?
+
+        # `true` is the default for `report_rescued_exceptions`, as specified in
+        # `sentry-rails/lib/sentry/rails/configuration.rb`.
+        true
       end
     end
   end