Prevent apps from being installed or removed during upgrades

src/freedombone-addremove

         return
     fi
 
+    if [ -f /tmp/.upgrading ]; then
+        dialog --title $"Cannot remove apps" \
+               --msgbox $"A system upgrade is happening, so apps cannot be removed at this time" 6 60
+        return
+    fi
+
     # ask for confirmation
     dialog --title $"Remove applications" \
            --backtitle $"Freedombone" \
     fi
 
     if [[ "$select_all_apps" != "add-all" ]]; then
+        if [ -f /tmp/.upgrading ]; then
+            dialog --title $"Cannot install apps" \
+                   --msgbox $"A system upgrade is happening, so apps cannot be installed at this time" 6 60
+            return
+        fi
+
         # ask for confirmation
         if [ $n -eq 1 ]; then
             dialog --title $"$installs" \

src/freedombone-utils-selector

 }
 
 function remove_apps {
+    if [ -f /tmp/.upgrading ]; then
+        return
+    fi
+
     app_index=0
     # shellcheck disable=SC2068
     for a in ${APPS_AVAILABLE[@]}
 function install_apps {
     is_interactive=$1
 
+    if [ -f /tmp/.upgrading ]; then
+        return
+    fi
+
     APP_INSTALLED_SUCCESS=1
 
     # interactive install configuration for each app