Report handler panics through the logger and answer 500 (closes #187)

internal/server/routes.go

@@ -51,7 +51,6 @@ func (s *Server) SetupRoutes() {
 }
 
 func (s *Server) setupGlobalMiddleware() {
-	s.router.Use(middleware.Recoverer)
 	s.router.Use(middleware.RequestID)
 	s.router.Use(s.mw.SecurityHeaders())
 	s.router.Use(s.mw.Logging())
@@ -64,8 +63,21 @@ func (s *Server) setupGlobalMiddleware() {
 	s.router.Use(s.mw.CORS())
 	s.router.Use(middleware.Timeout(requestTimeout))
 
+	// Panic recovery, deliberately here rather than first. It has to
+	// run inside every middleware that observes the response, so the
+	// 500 it writes is the status the access log records and the
+	// metrics count, and outside the sentryhttp handler below, whose
+	// Repanic option needs something further out to catch what it
+	// re-raises. chi's own middleware.Recoverer held the first slot
+	// until it was measured: on a current Go release it crashes
+	// inside its stack pretty-printer instead of recovering, so the
+	// connection dropped and the original panic was never reported.
+	// See https://git.eeqj.de/sneak/webhooker/issues/187.
+	s.router.Use(s.mw.Recoverer())
+
 	// Sentry error reporting (if SENTRY_DSN is set). Repanic is
-	// true so panics still bubble up to the Recoverer middleware.
+	// true so panics still bubble up to the Recoverer middleware
+	// registered immediately above.
 	if s.sentryEnabled {
 		sentryHandler := sentryhttp.New(sentryhttp.Options{
 			Repanic: true,