check fragment state before displaying the next screen

Author: codeismail-waver

rave_android/src/main/java/com/flutterwave/raveandroid/ach/AchFragment.java

@@ -157,9 +157,10 @@ public void showRedirectMessage(boolean active) {
 
     @Override
     public void showWebView(String authUrl, String flwRef) {
-
-        new RaveVerificationUtils(this, ravePayInitializer.isStaging(), ravePayInitializer.getPublicKey(), ravePayInitializer.getTheme())
-                .showWebpageVerificationScreen(authUrl);
+        if (isAdded()){
+            new RaveVerificationUtils(this, ravePayInitializer.isStaging(), ravePayInitializer.getPublicKey(), ravePayInitializer.getTheme())
+                    .showWebpageVerificationScreen(authUrl);
+        }
     }
 
     private void dismissDialog() {