Bash - Script error if folder with spaces

I have this script

#!/bin/bash

rename_files() {
   title="${1##*${2} - }"
   for filename in "$1/"*.*; do
   case "${filename##*.}" in
     doc|doc|doc)
       mkdir -p -m 777 "/Users/Desktop/Documents Share/Downloaded/${title}"
       new_path="/Users/Desktop/Documents Share/Downloaded/${title}/${title}.${filename##*.}"
       let "iters=1"
       while [ -f $new_path ] ; do
          new_path=$new_path"$iters"
          let "iters++"
       done
       echo "moving $filename -> $new_path"
       mv "${filename}" "${new_path}"
       ;;
   esac
   done
}

rename_category() {
  for path in "/Users/Desktop/Documents Share/Downloads/${1}"*; do
    rename_files "$path" "$1"
  done
}

rename_category DOC

This script automatically moves and renames files contained in /Users/Desktop/Documents Share/Downloaded. All is working fine if I use a folder called Documents instead of Documents Share. I tried to do use Documents Share but it doesn't work.

Here is the error log

/Users/Desktop/Script.sh: line 11: [: /Users/Desktop/Documents: binary operator expected

How can I solve it?