adapt to new dc_configure() error handling

errors that should be shown to the user
come from DC_EVENT_CONFIGURE_PROGRESS(data1=0) as data2 now;
there is no need to show the captured error any longer
(which was unreliable and hard to handle from core site).

there is some capturing-code left as needed for other parts,
but it is not used for configuration anymore.

res/values/strings.xml

@@ -374,6 +374,8 @@
     <string name="delete_account">Delete account</string>
     <string name="delete_account_ask">Are you sure you want to delete your account data?</string>
     <string name="switching_account">Switching account…</string>
+    <!-- Translations: %1$s will be replaced by a more detailed error message -->
+    <string name="configuration_failed_with_error">Configuration failed. Error: %1$s</string>
 
     <!-- share and forward messages -->
     <!-- Translators: Title shown above a chat/contact list; the user selects the recipient of the messages he wants to forward to -->

src/org/thoughtcrime/securesms/RegistrationActivity.java

@@ -20,7 +20,6 @@ import androidx.appcompat.app.AlertDialog;
 import android.text.Editable;
 import android.text.TextUtils;
 import android.text.TextWatcher;
-import android.text.util.Linkify;
 import android.util.Patterns;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -555,19 +554,7 @@ public class RegistrationActivity extends BaseActionBarActivity implements DcEve
                 dcContext.maybeStartIo(); // start-io is also needed on errors to make previous config work in case of changes
                 dcContext.endCaptureNextError();
                 progressDialog.dismiss();
-                if (dcContext.hasCapturedError()) {
-                    AlertDialog d = new AlertDialog.Builder(this)
-                            .setMessage(dcContext.getCapturedError())
-                            .setPositiveButton(android.R.string.ok, null)
-                            .create();
-                    d.show();
-                    try {
-                        //noinspection ConstantConditions
-                        Linkify.addLinks((TextView) d.findViewById(android.R.id.message), Linkify.WEB_URLS | Linkify.EMAIL_ADDRESSES);
-                    } catch(NullPointerException e) {
-                        e.printStackTrace();
-                    }
-                }
+                WelcomeActivity.maybeShowConfigurationError(this, data2);
             }
             else if (progress<1000/*progress in permille*/) {
                 int percent = (int)progress / 10;

src/org/thoughtcrime/securesms/WelcomeActivity.java

@@ -2,11 +2,14 @@ package org.thoughtcrime.securesms;
 
 import android.Manifest;
 import android.annotation.SuppressLint;
+import android.app.Activity;
 import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.Bundle;
+import android.text.util.Linkify;
 import android.view.View;
 import android.widget.Button;
+import android.widget.TextView;
 
 import androidx.annotation.NonNull;
 import androidx.appcompat.app.AlertDialog;
@@ -159,7 +162,7 @@ public class WelcomeActivity extends BaseActionBarActivity implements DcEventCen
         dcContext.captureNextError();
 
         if (!dcContext.setConfigFromQr(qrCode)) {
-            progressError();
+            progressError(dcContext.getCapturedError());
         }
 
         // calling configure() results in
@@ -168,15 +171,9 @@ public class WelcomeActivity extends BaseActionBarActivity implements DcEventCen
         dcContext.configure();
     }
 
-    private void progressError() {
-        dcContext.endCaptureNextError();
+    private void progressError(Object data2) {
         progressDialog.dismiss();
-        if (dcContext.hasCapturedError()) {
-            new AlertDialog.Builder(this)
-                    .setMessage(dcContext.getCapturedError())
-                    .setPositiveButton(android.R.string.ok, null)
-                    .show();
-        }
+        maybeShowConfigurationError(this, data2);
     }
 
     private void progressUpdate(int progress) {
@@ -198,12 +195,28 @@ public class WelcomeActivity extends BaseActionBarActivity implements DcEventCen
         finish();
     }
 
+    public static void maybeShowConfigurationError(Activity activity, Object data2) {
+        if (data2 instanceof String && !((String) data2).isEmpty()) {
+            AlertDialog d = new AlertDialog.Builder(activity)
+                .setMessage(((String) data2))
+                .setPositiveButton(android.R.string.ok, null)
+                .create();
+            d.show();
+            try {
+                //noinspection ConstantConditions
+                Linkify.addLinks((TextView) d.findViewById(android.R.id.message), Linkify.WEB_URLS | Linkify.EMAIL_ADDRESSES);
+            } catch(NullPointerException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
     @Override
     public void handleEvent(int eventId, Object data1, Object data2) {
         if (eventId== DcContext.DC_EVENT_IMEX_PROGRESS ) {
             long progress = (Long)data1;
             if (progress==0/*error/aborted*/) {
-                progressError();
+                progressError(dcContext.getCapturedError());
                 notificationController.close();
             }
             else if (progress<1000/*progress in permille*/) {
@@ -226,7 +239,7 @@ public class WelcomeActivity extends BaseActionBarActivity implements DcEventCen
         else if (!manualConfigure && eventId==DcContext.DC_EVENT_CONFIGURE_PROGRESS) {
             long progress = (Long)data1;
             if (progress==0/*error/aborted*/) {
-                progressError();
+                progressError(data2);
             }
             else if (progress<1000/*progress in permille*/) {
                 progressUpdate((int)progress);

src/org/thoughtcrime/securesms/connect/ApplicationDcContext.java

@@ -135,6 +135,7 @@ public class ApplicationDcContext extends DcContext {
     setStockTranslation(81, context.getString(R.string.systemmsg_ephemeral_timer_four_weeks));
     setStockTranslation(82, context.getString(R.string.videochat_invitation));
     setStockTranslation(83, context.getString(R.string.videochat_invitation_body));
+    setStockTranslation(84, context.getString(R.string.configuration_failed_with_error));
   }
 
   public File getImexDir() {