The return value of ff_draw_init and ff_draw_init2 are not checked in
most usages. However, if they return an error, they don't get to the
point where they set the attributes of the FFDrawContext. These
functions are typically used in conjunction with ff_draw_color, which
checks draw->desc->flags, causing a null pointer dereference.

Attaching patch with a fix to guard against this.

Thanks,
Nil