fix possible crash in SimpleRiftController when no HMD is connected

src/ACGL/HardwareSupport/SimpleRiftController.cc

@@ -150,15 +150,16 @@ SimpleRiftController::~SimpleRiftController()
 
 void SimpleRiftController::setPrediction( float _seconds )
 {
-    if ( _seconds >= 0.0f ) {
-        mORSensorFusion->SetPrediction( _seconds );
-    } else {
-        mORSensorFusion->SetPrediction( 0.0f, false );
+    if(getSuccessfulConnected()) {
+        if ( _seconds >= 0.0f ) {
+            mORSensorFusion->SetPrediction( _seconds );
+        } else {
+            mORSensorFusion->SetPrediction( 0.0f, false );
+        }
+        mPredictionTime = _seconds;
     }
-    mPredictionTime = _seconds;
 }
 
-
 glm::mat4 SimpleRiftController::getProjectionMatrixFromCamera()
 {
     if (!mCamera) return glm::mat4();