check fragment state before displaying the next screen

Author: codeismail-waver

rave_android/src/main/java/com/flutterwave/raveandroid/barter/BarterFragment.java

@@ -169,8 +169,10 @@ public void showFetchFeeFailed(String message) {
     public void loadBarterCheckout(String authUrlCrude, String flwRef) {
 
         this.flwRef = flwRef;
-        new RaveVerificationUtils(this, ravePayInitializer.isStaging(), ravePayInitializer.getPublicKey(), ravePayInitializer.getTheme())
-                .showBarterCheckoutScreen(authUrlCrude, flwRef);
+        if(isAdded()){
+            new RaveVerificationUtils(this, ravePayInitializer.isStaging(), ravePayInitializer.getPublicKey(), ravePayInitializer.getTheme())
+                    .showBarterCheckoutScreen(authUrlCrude, flwRef);
+        }
 
     }