Create Check Dataset Statements

src/main/java/seng202/group9/GUI/AirlineGraphController.java

@@ -19,6 +19,9 @@ public class AirlineGraphController extends Controller{
 
     @Override
     public void load() {
+        if (!checkDataset()){
+            return;
+        }
         dataset = getParent().getCurrentDataset();
         session = getParent().getSession();
     }

src/main/java/seng202/group9/GUI/AirportGraphController.java

@@ -17,6 +17,9 @@ public class AirportGraphController extends Controller{
 
     @Override
     public void load() {
+        if (!checkDataset()){
+            return;
+        }
         dataset = getParent().getCurrentDataset();
         session = getParent().getSession();
     }

src/main/java/seng202/group9/GUI/RouteGraphController.java

@@ -17,6 +17,9 @@ public class RouteGraphController extends Controller{
 
     @Override
     public void load() {
+        if (!checkDataset()){
+            return;
+        }
         dataset = getParent().getCurrentDataset();
         session = getParent().getSession();
     }