updated serial send with error case

src/main.rs

@@ -164,7 +164,10 @@ fn main() {
                     // PID controller
 
                     // send voltage to motors.
-                    port.write(&message[0..message_length]).unwrap();
+                    match port.write(&message[0..message_length]) {
+                        Ok(n) => {println!("Controller: sent {} bytes to arduino!", n);},
+                        Err(e) => {println!("Controller: could not write to arduino: {}", e); },
+                    }
 
                 }