harden extraText/extraSubject

Signed-off-by: tobiasKaminsky <tobias@kaminsky.me>

src/main/java/com/owncloud/android/ui/activity/ReceiveExternalFilesActivity.java

@@ -355,14 +355,22 @@ public class ReceiveExternalFilesActivity extends FileActivity
             mFilenameSuffix = new ArrayList<>();
             mText = new ArrayList<>();
 
-            String subjectText = getArguments().getString(KEY_SUBJECT_TEXT);
-            String extraText = getArguments().getString(KEY_EXTRA_TEXT);
+            String subjectText = "";
+            String extraText = "";
+            if (getArguments() != null) {
+                if (getArguments().getString(KEY_SUBJECT_TEXT) != null) {
+                    subjectText = getArguments().getString(KEY_SUBJECT_TEXT);
+                }
+                if (getArguments().getString(KEY_EXTRA_TEXT) != null) {
+                    extraText = getArguments().getString(KEY_EXTRA_TEXT);
+                }
+            }
 
-            LayoutInflater layout = LayoutInflater.from(getActivity().getBaseContext());
+            LayoutInflater layout = LayoutInflater.from(requireContext());
             View view = layout.inflate(R.layout.upload_file_dialog, null);
 
             ArrayAdapter<String> adapter
-                    = new ArrayAdapter<>(getActivity().getBaseContext(), android.R.layout.simple_spinner_item);
+                    = new ArrayAdapter<>(requireContext(), android.R.layout.simple_spinner_item);
             adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
 
             int selectPos = 0;
@@ -393,7 +401,7 @@ public class ReceiveExternalFilesActivity extends FileActivity
 
                 selectPos = PreferenceManager.getUploadUrlFileExtensionUrlSelectedPos(getActivity());
                 mFileCategory = CATEGORY_URL;
-            } else if (extraText != null && isIntentFromGoogleMap(subjectText, extraText)) {
+            } else if (isIntentFromGoogleMap(subjectText, extraText)) {
                 String str = getString(R.string.upload_file_dialog_filetype_googlemap_shortcut);
                 String texts[] = extraText.split("\n");
                 mText.add(internetShortcutUrlText(texts[2]));
@@ -456,7 +464,7 @@ public class ReceiveExternalFilesActivity extends FileActivity
 
         @NonNull
         private Dialog createFilenameDialog(View view, final EditText userInput, final Spinner spinner) {
-            Builder builder = new Builder(getActivity());
+            Builder builder = new Builder(requireActivity());
             builder.setView(view);
             builder.setTitle(R.string.upload_file_dialog_title);
             builder.setPositiveButton(R.string.common_ok, (dialog, id) -> {