ActionDispatch::Executor: report errors handled by ShowExceptions

Fix: rails#51002

In the default middleware stack, the `ShowExceptions` middleware is
lower than `ActionDispatch::Execturor` and will handle most exceptions
causing `Executor` not to witness any.

Instead we need to rely on `action_dispatch.exception` being added
into the request env.

actionpack/lib/action_dispatch/middleware/executor.rb

@@ -14,6 +14,9 @@ def call(env)
       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")
+        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

@@ -45,12 +45,15 @@ def call(env)
       def render_exception(request, wrapper)
         status = wrapper.status_code
         request.set_header "action_dispatch.exception", wrapper.unwrapped_exception
-        request.set_header "action_dispatch.original_path", request.path_info
-        request.set_header "action_dispatch.original_request_method", request.raw_request_method
-        fallback_to_html_format_if_invalid_mime_type(request)
-        request.path_info = "/#{status}"
-        request.request_method = "GET"
-        response = @exceptions_app.call(request.env)
+
+        sub_request = request.dup
+        sub_request.set_header "action_dispatch.original_path", request.path_info
+        sub_request.set_header "action_dispatch.original_request_method", request.raw_request_method
+
+        fallback_to_html_format_if_invalid_mime_type(sub_request)
+        sub_request.path_info = "/#{status}"
+        sub_request.request_method = "GET"
+        response = @exceptions_app.call(sub_request.env)
         response[1][Constants::X_CASCADE] == "pass" ? pass_response(status) : response
       rescue Exception => failsafe_error
         $stderr.puts "Error during failsafe response: #{failsafe_error}\n  #{failsafe_error.backtrace * "\n  "}"

actionpack/test/dispatch/executor_test.rb

@@ -119,6 +119,33 @@ def test_body_abandoned
     assert_equal requests_count - 1, completed
   end
 
+  def test_error_reporting
+    raised_error = nil
+    error_report = assert_error_reported do
+      raised_error = assert_raises TypeError do
+        call_and_return_body { 1 + "1" }
+      end
+    end
+    assert_same raised_error, error_report.error
+  end
+
+  def test_error_reporting_with_show_exception
+    middleware = Rack::Lint.new(
+      ActionDispatch::Executor.new(
+        ActionDispatch::ShowExceptions.new(
+          Rack::Lint.new(->(_env) { 1 + "1" }),
+          ->(_env) { [500, {}, ["Oops"]] },
+        ),
+        executor,
+      )
+    )
+
+    env = Rack::MockRequest.env_for("", {})
+    error_report = assert_error_reported do
+      middleware.call(env)
+    end
+  end
+
   private
     def call_and_return_body(&block)
       app = block || proc { [200, {}, []] }