Do not report rendered errors except 500

In `4067c9565a5da78a72e375a2d959000147f02c34` `ActionDispatch::Executor`
started to report all errors, even the ones that were "handled" by the application.
This leads to errors like `ActionController::RoutingError` polluting error trackers
while not being actionable since they do not represent an exceptional situation.

This commit changes the behavior to only report errors that are not
considered "handled" based on the `ActionDispatch::ExceptionWrapper.rescue_responses` list.

actionpack/lib/action_dispatch/middleware/executor.rb

@@ -14,9 +14,12 @@ module ActionDispatch
       state = @executor.run!(reset: true)
       begin
         response = @app.call(env)
-        if rendered_error = env["action_dispatch.exception"]
-          @executor.error_reporter.report(rendered_error, handled: false, source: "application.action_dispatch")
+
+        if env["action_dispatch.report_exception"]
+          error = env["action_dispatch.exception"]
+          @executor.error_reporter.report(error, handled: false, source: "application.action_dispatch")
         end
+
         returned = response << ::Rack::BodyProxy.new(response.pop) { state.complete! }
       rescue => error
         @executor.error_reporter.report(error, handled: false, source: "application.action_dispatch")

actionpack/lib/action_dispatch/middleware/show_exceptions.rb

@@ -35,6 +35,7 @@ module ActionDispatch
       backtrace_cleaner = request.get_header("action_dispatch.backtrace_cleaner")
       wrapper = ExceptionWrapper.new(backtrace_cleaner, exception)
       request.set_header "action_dispatch.exception", wrapper.unwrapped_exception
+      request.set_header "action_dispatch.report_exception", !wrapper.rescue_response?
 
       if wrapper.show?(request)
         render_exception(request.dup, wrapper)

actionpack/test/dispatch/executor_test.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "abstract_unit"
+require "active_support/core_ext/object/with"
 
 class ExecutorTest < ActiveSupport::TestCase
   class MyBody < Array
@@ -147,6 +148,28 @@ class ExecutorTest < ActiveSupport::TestCase
     assert_instance_of TypeError, error_report.error
   end
 
+  class BusinessAsUsual < StandardError; end
+
+  def test_handled_error_is_not_reported
+    middleware = Rack::Lint.new(
+      ActionDispatch::Executor.new(
+        ActionDispatch::ShowExceptions.new(
+          Rack::Lint.new(->(_env) { raise BusinessAsUsual }),
+          ->(env) { [418, {}, ["I'm a teapot"]] },
+        ),
+        executor,
+      )
+    )
+
+    env = Rack::MockRequest.env_for("", {})
+    ActionDispatch::ExceptionWrapper.with(rescue_responses: { BusinessAsUsual.name => 418 }) do
+      assert_no_error_reported do
+        response = middleware.call(env)
+        assert_equal 418, response[0]
+      end
+    end
+  end
+
   private
     def call_and_return_body(&block)
       app = block || proc { [200, {}, []] }