lib/config: Make folder marker change non fatal

lib/config/config.go

@@ -395,7 +395,7 @@ func convertV22V23(cfg *Configuration) {
 				fs.Hide(".stfolder") // ignore error
 			}
 			if err != nil {
-				l.Fatalln("failed to upgrade folder marker:", err)
+				l.Infoln("Failed to upgrade folder marker:", err)
 			}
 		}
 	}