DialWindow - Fix rolling average initialization

Reported in #4298

src/Train/DialWindow.cpp

@@ -149,8 +149,10 @@ DialWindow::telemetryUpdate(const RealtimeData &rtData)
         series == RealtimeData::Cadence) {
 
         sum += value;
-        int j = index-(count<average*5?count:average*5);
-        sum -= rolling[(j>=0?j:150+j)];
+        if (count >= average*5) {
+            int j = index - average*5;
+            sum -= rolling[(j>=0?j:150+j)];
+        }
 
         //store value
         rolling[index] = value;

src/Train/NullController.cpp

@@ -63,6 +63,7 @@ void NullController::getRealtimeData(RealtimeData &rtData) {
     rtData.setName((char *)"Null");
     rtData.setWatts(load + ((rand()%25)-15)); // for testing virtual power
     rtData.setLoad(load);
+    rtData.setLRBalance(50 + ((rand()%20)-10)); // for testing LRBalance widget
 
     // Compute speed from principles and randomized power instead of randomizing it independantly.
     // This makes it easier to eyeball rlv behavior and test gpx tools using rides generated by