fix msvc

src/objects/base.c

@@ -1,5 +1,6 @@
 #include "pocketpy/objects/base.h"
 
-PyVar pkpy_NULL = {.type=0, .is_ptr=false};
-PyVar pkpy_OP_CALL = {.type=tp_op_call, .is_ptr=false};
-PyVar pkpy_OP_YIELD = {.type=tp_op_yield, .is_ptr=false};
+PyVar pkpy_NULL = {.type=0, .is_ptr=false, .extra=0, ._i64=0};
+PyVar pkpy_OP_CALL = {.type=tp_op_call, .is_ptr=false, .extra=0, ._i64=0};
+PyVar pkpy_OP_YIELD = {.type=tp_op_yield, .is_ptr=false, .extra=0, ._i64=0};
+