When running todo report with your DONE_FILE being in a directory with
a space in the path (ex: C:\My Documents), you will get an "ambiguous
redirect" error. This is because the $DONE_FILE variable doesn't have
""s around it on line 637 of todo.sh. The error doesn't appear after
adding the ""s.

Before:
sed '/^x /!d' "$TODO_FILE" >> $DONE_FILE

After:
sed '/^x /!d' "$TODO_FILE" >> "$DONE_FILE"