gcc complains that he can't assure if switch-enum is complete

include/picrin/value.h

@@ -199,6 +199,8 @@ pic_type(pic_value v)
     return PIC_TT_EOF;
   case PIC_VTYPE_HEAP:
     return ((struct pic_object *)pic_ptr(v))->tt;
+  default:
+    return -1;                  /* logic flaw */
   }
 }