Set default theme variable during upgrade

install/upgrade/versions/latest.sh

@@ -13,7 +13,7 @@ source $HESTIA/func/main.sh
 # Set default theme
 if [ -z $THEME ]; then
     echo "(*) Enabling support for themes..."
-    $BIN/v-change-sys-theme default
+    $BIN/v-change-sys-config-value 'THEME' default
 fi
 
 # Replace dhparam 1024 with dhparam 4096