fix crash when sending btc (#686)

app/src/main/java/com/m2049r/xmrwallet/fragment/send/SendBtcConfirmWizardFragment.java

@@ -204,7 +204,7 @@ public class SendBtcConfirmWizardFragment extends SendWizardFragment implements
         ((TxDataBtc) sendListener.getTxData()).setXmrtoUuid(xmrtoStatus.getUuid());
         // TODO make method in TxDataBtc to set both of the above in one go
         sendListener.commitTransaction();
-        pbProgressSend.setVisibility(View.VISIBLE);
+        getActivity().runOnUiThread(() -> pbProgressSend.setVisibility(View.VISIBLE));
     }
 
     @Override

app/src/main/java/com/m2049r/xmrwallet/fragment/send/SendConfirmWizardFragment.java

@@ -131,12 +131,7 @@ public class SendConfirmWizardFragment extends SendWizardFragment implements Sen
 
     void send() {
         sendListener.commitTransaction();
-        getActivity().runOnUiThread(new Runnable() {
-            @Override
-            public void run() {
-                pbProgressSend.setVisibility(View.VISIBLE);
-            }
-        });
+        getActivity().runOnUiThread(() -> pbProgressSend.setVisibility(View.VISIBLE));
     }
 
     @Override