Bugfix when calling destructor without a running thread

AutonomousMode/lfr.cpp

@@ -19,7 +19,10 @@ LFR::LFR(int videoHeight, int videoWidth, int thresholdBinary, int gaussKernelSi
 LFR::~LFR()
 {
     endLoop();
-    thread->join();
+    if(thread)
+    {
+        thread->join();
+    }
 }
 
 void LFR::removeListener(LFR::ListenerKey key)