Fix #2018 type assertion on untyped nil within a ternary if expression

src/check_expr.cpp

@@ -7403,6 +7403,7 @@ ExprKind check_ternary_if_expr(CheckerContext *c, Operand *o, Ast *node, Type *t
 		    check_cast_internal(c, &y, type_hint)) {
 			convert_to_typed(c, o, type_hint);
 			update_untyped_expr_type(c, node, type_hint, !is_type_untyped(type_hint));
+			o->type = type_hint;
 		}
 	}
 	return kind;