Fix a bug where arduino would crash on incorrectly sized i2c payload

crawler_software/arduino/crawler_slave/crawler_slave.ino

@@ -41,8 +41,7 @@ void loop() {
 
 // This method runs when we receive a message
 void receiveEvent(int n) {
-  Wire.read();
-  digitalWrite(LED_BUILTIN, HIGH);
+  Wire.read(); // Remove smbus trash
   if (true) { // Dont do anything if this is not true
     id  = Wire.read(); // ID of the servo/device to access
     val = Wire.read(); // Value to assign
@@ -56,5 +55,9 @@ void receiveEvent(int n) {
         break;
     }
   }
-  digitalWrite(LED_BUILTIN, LOW);
+
+  // Prevents a bug where if bytes are left in buffer, arduino crashes.
+  while (Wire.available()) {
+    Wire.read();
+  }
 }