fix: improve error handling to prevent panics

In some scenarios, the status code of the response object was set to
200, but the error was non nil. The middleware was logging 200, but echo
was actually responding with 500.

In other scenarios, the status code of the response was set to 500, but
the error was nil. The middleware was checking the status code of the
response and if it was not ok, it tried to log the error message, which
resulted in a panic.

This patch should make error handling more robust.

Signed-off-by: Michal Wasilewski <[email protected]>

middleware.go

@@ -51,6 +51,10 @@ func NewWithConfig(logger *slog.Logger, config Config) echo.MiddlewareFunc {
 
 			err = next(c)
 
+			if err != nil {
+				c.Error(err)
+			}
+
 			requestID := req.Header.Get(echo.HeaderXRequestID)
 			if requestID == "" {
 				requestID = res.Header().Get(echo.HeaderXRequestID)
@@ -91,9 +95,17 @@ func NewWithConfig(logger *slog.Logger, config Config) echo.MiddlewareFunc {
 
 			switch {
 			case status >= http.StatusInternalServerError:
-				logger.LogAttrs(context.Background(), config.ServerErrorLevel, err.Error(), attributes...)
+				var errMsg string
+				if err != nil {
+					errMsg = err.Error()
+				}
+				logger.LogAttrs(context.Background(), config.ServerErrorLevel, errMsg, attributes...)
 			case status >= http.StatusBadRequest && status < http.StatusInternalServerError:
-				logger.LogAttrs(context.Background(), config.ClientErrorLevel, err.Error(), attributes...)
+				var errMsg string
+				if err != nil {
+					errMsg = err.Error()
+				}
+				logger.LogAttrs(context.Background(), config.ClientErrorLevel, errMsg, attributes...)
 			case status >= http.StatusMultipleChoices && status < http.StatusBadRequest:
 				logger.LogAttrs(context.Background(), config.DefaultLevel, "Redirection", attributes...)
 			default: