[Libreoffice] Questions about ./sdext/source/minimizer/unodialog.cxx

Hello,

I'm currently running a cppcheck on the clone directory (i had try to 
launch cppcheck on the build/libreoffice... but it seemed it freezed).
I've seen this issue :
[./extensions/sdext/source/minimizer/unodialog.cxx:359]: (error) 
Division by zero

I opened the file and saw this :
sal_Int32 UnoDialog::getMapsFromPixels( sal_Int32 nPixels ) const
{
    double dMaps = 0;
    try
    {
        sal_Int32 nMapWidth = 0;
        const OUString sWidth( RTL_CONSTASCII_USTRINGPARAM( "Width" ) );
        if ( mxDialogModelPropertySet->getPropertyValue( sWidth  ) >>= 
nMapWidth )
        {
            Reference< XWindow > xWindow( mxDialog, UNO_QUERY_THROW );
            double pxWidth = xWindow->getPosSize().Width;
            double mapRatio = ( pxWidth / nMapWidth ); ------- HERE IS 
THE DIVSION BY ZERO DETECTED BY CPPCHECK
            dMaps = nPixels / mapRatio;
        }
    }
    catch ( Exception& )
    {
    }
    return static_cast< sal_Int32 >( dMaps );
}

Questions :
- what's the use of nMapWidth since it's initialized to 0 and stays at 
this value ?
- What's the use of making a right rotation of bits of 0 ? 
(mxDialogModelPropertySet->getPropertyValue( sWidth  ) >>= nMapWidth)
- what's the use of a catch with nothing in it except for hidding a bug ?