Bugfix: prevent crash when ending a recording (barometer present).

Fixes #1766.

src/main/java/de/dennisguse/opentracks/sensors/sensorData/SensorDataSet.java

@@ -120,6 +120,10 @@ public final class SensorDataSet {
             return;
         }
         if (value instanceof AtmosphericPressure) {
+            if (this.barometer == null) {
+                //TODO Quick fix. This shouldn't happen, but it does. May be a race condition?
+                return;
+            }
             this.barometer.add((Raw<AtmosphericPressure>) data);
             return;
         }