vala: Handle unavailable type-symbol in Constant.check_const_type()

This caused criticals like:

  vala_typesymbol_is_subtype_of: assertion 'self != NULL' failed

diff --git a/vala/valaconstant.vala b/vala/valaconstant.vala
index 809cb883dba241133afe6e4ffe49e207bd0a1f6e..b0beddc2b3d7ff437d80310d353c13f610130bad 100644 (file)
--- a/vala/valaconstant.vala
+++ b/vala/valaconstant.vala
@@ -190,8 +190,8 @@ public class Vala.Constant : Symbol {
                } else if (type is ArrayType) {
                        unowned ArrayType array_type = (ArrayType) type;
                        return check_const_type (array_type.element_type, context);
-               } else if (type.type_symbol.is_subtype_of (context.analyzer.string_type.type_symbol)) {
-                       return true;
+               } else if (type.type_symbol != null) {
+                       return type.type_symbol.is_subtype_of (context.analyzer.string_type.type_symbol);
                } else {
                        return false;
                }