Revert "Improve unhandled error handling in prod mode"

This reverts commit c2079276ebfa00cc03c738af4af99348deb5a287.

router.go

@@ -368,8 +368,8 @@ func (p *ControllerRegistor) ServeHTTP(rw http.ResponseWriter, r *http.Request)
 			if _, ok := err.(middleware.HTTPException); ok {
 				// catch intented errors, only for HTTP 4XX and 5XX
 			} else {
-				handler := p.getErrorHandler(fmt.Sprint(err))
-				if ErrorsShow {
+				errstr := fmt.Sprint(err)
+				if handler, ok := middleware.ErrorMaps[errstr]; ok && ErrorsShow {
 					handler(rw, r)
 				} else {
 					if !RecoverPanic {
@@ -865,24 +865,6 @@ Admin:
 	}
 }
 
-// there always should be error handler that sets error code accordingly for all unhandled errors
-// in order to have custom UI for error page it's necessary to override "500" error
-func (p *ControllerRegistor) getErrorHandler(errorCode string) func(rw http.ResponseWriter, r *http.Request) {
-	handler := middleware.SimpleServerError
-	ok := true
-	if errorCode != "" {
-		handler, ok = middleware.ErrorMaps[errorCode]
-		if !ok {
-			handler, ok = middleware.ErrorMaps["500"]
-		}
-		if !ok || handler == nil {
-			handler = middleware.SimpleServerError
-		}
-	}
-
-	return handler
-}
-
 //responseWriter is a wrapper for the http.ResponseWriter
 //started set to true if response was written to then don't execute other handler
 type responseWriter struct {