Check image value before use

[radarhere]

Similar to #8398, check the value of imIn before using it.

Pillow/src/libImaging/Geometry.c

Lines 794 to 801 in b557876

	ImagingTransformFilter filter = getfilter(imIn, filterid);
	if (!filter) {
	return (Imaging)ImagingError_ValueError("bad filter number");
	}
	if (!imOut || !imIn || strcmp(imIn->mode, imOut->mode) != 0) {
	return (Imaging)ImagingError_ModeError();
	}

Pillow/src/libImaging/Geometry.c

Lines 709 to 712 in b557876

	getfilter(Imaging im, int filterid) {
	switch (filterid) {
	case IMAGING_TRANSFORM_NEAREST:
	if (im->image8) {

[hugovk]

(I misclicked the "update branch" button, but never mind.)