Upgrade to new go errors and some minor fixes and improvements including easier debugging of invalid routes and e.t.c.

Former-commit-id: 5809157b952ccc61a67a9861470774b3a6fee024

view/html.go

@@ -226,6 +226,11 @@ func (s *HTMLEngine) Load() error {
 	if err != nil {
 		return err
 	}
+
+	if _, err := os.Stat(dir); os.IsNotExist(err) {
+		return err
+	}
+
 	// change the directory field configuration, load happens after directory has been set, so we will not have any problems here.
 	s.directory = dir
 	return s.loadDirectory()