Don't throw exception when the copy of the image is failing.

#6569

@rbran100 Catching the error during the validation cannot be done here since the calling to `os_copy_file` occurring in a late part of the submission form. If you'd like to catch the exception in the validation a lot of the logic need to move to the validation callback - i don't think this is the right thing to do.

But i did display the error when it happens.