NULL is returned, then error will be set.
Possible errors are in the gdkPixbufNewFromFileAtScale(filename, width, height, preserve.aspect.ratio, .errwarn = TRUE)TRUE to preserve the image's aspect ratioNULL
if any of several error conditions occurred: the file could not be opened,
there was no loader for the file's format, there was not enough memory to
allocate the image buffer, or the image file contained invalid data.width of -1 will cause the image
to be scaled to the exact given height, and a height of -1 will cause
the image to be scaled to the exact given width. When not preserving
aspect ratio, a width or height of -1 means to not scale the image
at all in that dimension. Negative values for width and height are
allowed since 2.8. Since 2.6