stmhal: Bug fix for usocket's accept and setsockopt methods.

accept might raise an exception, in which case the new socket is not
fully created.  It has a finaliser so will run close() method when GC'd.
Before this patch close would try to close an invalid socket.  Now
fixed.

setsockopt took address of stack value which became out of scope.  Now
fixed.

stmhal/modusocket.c

@@ -132,10 +132,11 @@ STATIC mp_obj_t socket_accept(mp_obj_t self_in) {
     mod_network_socket_obj_t *self = self_in;
 
     // create new socket object
+    // starts with empty NIC so that finaliser doesn't run close() method if accept() fails
     mod_network_socket_obj_t *socket2 = m_new_obj_with_finaliser(mod_network_socket_obj_t);
     socket2->base.type = (mp_obj_t)&socket_type;
-    socket2->nic = self->nic;
-    socket2->nic_type = self->nic_type;
+    socket2->nic = MP_OBJ_NULL;
+    socket2->nic_type = NULL;
 
     // accept incoming connection
     uint8_t ip[MOD_NETWORK_IPADDR_BUF_SIZE];
@@ -145,6 +146,10 @@ STATIC mp_obj_t socket_accept(mp_obj_t self_in) {
         nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(_errno)));
     }
 
+    // new socket has valid state, so set the NIC to the same as parent
+    socket2->nic = self->nic;
+    socket2->nic_type = self->nic_type;
+
     // make the return value
     mp_obj_tuple_t *client = mp_obj_new_tuple(2, NULL);
     client->items[0] = socket2;
@@ -281,8 +286,9 @@ STATIC mp_obj_t socket_setsockopt(mp_uint_t n_args, const mp_obj_t *args) {
 
     const void *optval;
     mp_uint_t optlen;
+    mp_int_t val;
     if (mp_obj_is_integer(args[3])) {
-        mp_int_t val = mp_obj_int_get_truncated(args[3]);
+        val = mp_obj_int_get_truncated(args[3]);
         optval = &val;
         optlen = sizeof(val);
     } else {