Fix erroneous err='' output in worktree rm

worktree/worktree.plugin.zsh

@@ -136,6 +136,7 @@ Manage git worktrees by branch name."
       wt_list=$(git worktree list --porcelain)
       local failed=0
       local wt_path
+      local err
       for branch in "${branches[@]}"; do
         wt_path=$(echo "$wt_list" | awk -v b="$branch" \
           '/^worktree /{ sub(/^worktree /, ""); p=$0 } /^branch refs\/heads\//{ sub(/^branch refs\/heads\//, ""); if($0==b) print p }')
@@ -152,7 +153,6 @@ Manage git worktrees by branch name."
         fi
         local -a rm_args=()
         (( force )) && rm_args+=(--force)
-        local err
         if err=$(git worktree remove "${rm_args[@]}" "$wt_path" 2>&1); then
           :
         elif [[ "$err" == *"working trees containing submodules"* ]]; then