Hello!

Suppose the following image operation:
var stream = gm('piano.png').crop(100, 100, 0, 0).stream('jpg')
How can I be notified of processing errors (such as if "piano.png" couldn't be opened)?

I've tried the alternative:
gm('piano.png').crop(100, 100, 0, 0).stream('jpg', function (err, stdout, stderr) {...})
Even in "piano.png" doesn't exists, the err parameter in the callback is null (that is expected).
If I attach a data event listener on stream stderr, I'm able to receive error messages - and detect processing errors.
But I've tried with a PNG file (http://www.iphonestheme.com/uploads/allimg/130206/1-1302061353440-L.png), and although the image was successfully processed, I still got some warnings coming from the stderr stream:

convert: iCCP: known incorrect sRGB profile `/Users/rgermano/iG/workspaces/iglr-app/test/resources/img-validator/piano_600x1636.png' @ warning/png.c/MagickPNGWarningHandler/1830.

Is there an approach using streams to catch processing errors only (not warnings)?

Thanks!
Ricardo