Invert logic to reduce nesting

Signed-off-by: DL6ER <dl6er@dl6er.de>

gravity.sh

@@ -149,8 +149,11 @@ database_table_from_file() {
 
 # Migrate pre-v5.0 list files to database-based Pi-hole versions
 migrate_to_database() {
-  # Create database file if not present
-  if [ ! -e "${gravityDBfile}" ]; then
+  # Create database file only if not present
+  if [ -e "${gravityDBfile}" ]; then
+    return 0
+  fi
+
   echo -e "  ${INFO} Creating new gravity database"
   generate_gravity_database
 
@@ -175,7 +178,6 @@ migrate_to_database() {
     echo -e "  ${INFO} Migrating content of ${regexFile} into new database"
     database_table_from_file "regex" "${regexFile}"
   fi
-  fi
 }
 
 # Determine if DNS resolution is available before proceeding