feat(git): enhance git folder scripts with validation and error handling for missing submodules and existing directories

bin/switch-git-folder

@@ -13,10 +13,16 @@ switch-git-folder() {
     local git_branch="$1"
     local git_folders=$(ls-git-folder "$2")
     for git_folder in $git_folders; do
-
         git_folder="${git_folder#./}"
 
         local shallow=$(git config --file .gitmodules --get submodule."$git_folder".shallow)
+        local git_folder_path=$(git config --file .gitmodules --get submodule."$git_folder".path)
+        local git_folder_url=$(git config --file .gitmodules --get submodule."$git_folder".url)
+        
+        if [[ -z "$git_folder_path" ]] || [[ -z "$git_folder_url" ]]; then
+            echo "Skipping: '$git_folder' not defined in .gitmodules."
+            continue
+        fi
 
         if [[ "$shallow" = "true" ]]; then
             echo "Fetch branch $git_branch (shallow) from origin and then switch."