display: Do not set zero-filled packets if a packet cannot be encoded.

display/firmware/src/radio.rs

         let mut get_values = GetValues {
             count: value_types.len() as u8,
             location,
-            types_: [ValueType::Time; 8],
+            types: [ValueType::Time; 8],
         };
-        get_values.types_[0..value_types.len()].copy_from_slice(value_types);
+        get_values.types[0..value_types.len()].copy_from_slice(value_types);
         self.send_packet(Packet::GetValues(get_values));
 
         // Receive the response.
         let mut tx = self.nrf24.take().unwrap().tx().unwrap();
         while !tx.can_send().unwrap() {}
         let mut payload = [0u8; 32];
-        packet.encode_and_encrypt(
+        if !packet.encode_and_encrypt(
             &KEY,
             self.radio.salt.unwrap_or(DEVICE_ID as u64),
             &mut payload,
-        );
+        ) {
+            return false;
+        }
         tx.send(&payload).unwrap();
         // TODO: Check whether the packet arrived.