Potential Null dereference

[ManSoSec]

I think a null check on dwg->dwg_class is missing here:

libredwg/src/print.c

Lines 588 to 594 in 785df5f

	if (i > 0 && i < (int)dwg->num_classes)
	{
	klass = &dwg->dwg_class[i];
	is_entity = klass ? dwg_class_is_entity (klass) : 0;
	}
	// properly dwg_decode_object/_entity for eed, reactors, xdic
	if (klass && !is_entity)

While it is done here, which is a similar cases:

libredwg/src/free.c

Lines 727 to 732 in 785df5f

	if (dwg->dwg_class && i >= 0 && i < (int)dwg->num_classes)
	{
	klass = &dwg->dwg_class[i];
	is_entity = klass ? dwg_class_is_entity (klass) : 0;
	}
	if (klass && !is_entity)

[rurban]

make scan-build complains about 6 of those.

[rurban]

Only with free we could have freed dwg->dwg_class already. Will not happen with print, where num_classes will be 0 then.