codegen: Guard get_default_ref_sink_function() against null base-class

diff --git a/codegen/valaccodeattribute.vala b/codegen/valaccodeattribute.vala
index 9d7bc1783959919d920893da5bc4486ff0149aaf..f6b1e4c3df268887d98ec269a27914380e5119b9 100644 (file)
--- a/codegen/valaccodeattribute.vala
+++ b/codegen/valaccodeattribute.vala
@@ -883,7 +883,10 @@ public class Vala.CCodeAttribute : AttributeCache {
 
        private string get_default_ref_sink_function () {
                if (sym is Class) {
-                       return get_ccode_ref_sink_function (((Class) sym).base_class);
+                       unowned Class? base_class = ((Class) sym).base_class;
+                       if (base_class != null) {
+                               return get_ccode_ref_sink_function (base_class);
+                       }
                } else if (sym is Interface) {
                        foreach (var prereq in ((Interface) sym).get_prerequisites ()) {
                                string ref_sink_func = get_ccode_ref_sink_function ((ObjectTypeSymbol) prereq.data_type);