ImageIO.read() returns null if the input image type is not supported (which occurs when trying to read a PPM file), so output a friendly error instead of letting the next line throw a null pointer exception.


git-svn-id: svn://svn.code.sf.net/p/libjpeg-turbo/code/trunk@918 632fc199-4ca6-4c93-a231-07263d6284db