Handle complex arguments in imagesc (bug #36866) * image.m: Don't error out with complex images, show real part and warn, like imshow. * graphics.in.h (array_property): Change type_constraint to std::set instead of std::list. (array_property::add_constraint): Use std::set::insert instead of std::list::push_back. (image::properties::init): Add new "real" constraint. * graphics.cc (array_property::validate): Check for new "real" type constraint. * gl-render.cc (opengl_renderer::draw_image): Abort if no image data is found.

--- a/src/gl-render.cc
+++ b/src/gl-render.cc
@@ -2488,6 +2488,10 @@
   Matrix x = props.get_xdata ().matrix_value ();
   Matrix y = props.get_ydata ().matrix_value ();
 
+  // Someone wants us to draw an empty image? No way.
+  if (x.is_empty () || y.is_empty ())
+    return;
+
   if (w > 1 && x(1) == x(0))
     x(1) = x(1) + (w-1);