Analytics: small changes (2)

- Added checks in UnitGenerator

analytics/includes/UnitGenerator.h

@@ -224,7 +224,7 @@ public:
                     continue;
                 }
             }
-
+            
         if(ondemand) {
             shared_ptr<UnitTemplate<SBase>> unPtr = make_shared<UnitTemplate<SBase>>(SensorNavigator::templateKey, inputs, outputs);
             unPtr->setInputMode(inputMode);
@@ -232,6 +232,11 @@ public:
         }
 
         delete units;
+        if(unitObjects->empty()) {
+            delete unitObjects;
+            throw invalid_argument("UnitGenerator: No units were created!");
+        }
+        
         return unitObjects;
     }