less: Fix issues with the map file on Windows. See the comment in the code for more information. Also, only wrap the opening of the map file in a try/except clause, since we want to catch the situation where the map file is missing only.

@echo off
setlocal

set CUR_DIR=%~dp0
set CHEF=%CUR_DIR%..\bin\chef
set OUT_DIR=%CUR_DIR%..\piecrust\resources\messages
set ROOT_DIR=%CUR_DIR%messages

%CHEF% --root=%ROOT_DIR% bake -o %OUT_DIR%
del %OUT_DIR%\index.html