py/vm: Simplify handling of special-case STOP_ITERATION in yield from.

There's no need to have MP_OBJ_NULL a special case, the code can re-use
the MP_OBJ_STOP_ITERATION value to signal the special case and the VM can
detect this with only one check (for MP_OBJ_STOP_ITERATION).

1 files changed, 1 insertions, 2 deletions

diff --git a/py/vm.c b/py/vm.c
index 416de6b1a..2a8e3c990 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -1178,8 +1178,7 @@ yield:
                     } else if (ret_kind == MP_VM_RETURN_NORMAL) {
                         // Pop exhausted gen
                         sp--;
-                        // TODO: When ret_value can be MP_OBJ_NULL here??
-                        if (ret_value == MP_OBJ_NULL || ret_value == MP_OBJ_STOP_ITERATION) {
+                        if (ret_value == MP_OBJ_STOP_ITERATION) {
                             // Optimize StopIteration
                             // TODO: get StopIteration's value
                             PUSH(mp_const_none);