Added fail safe

app/src/main/java/eu/faircode/email/ApplicationEx.java

@@ -249,6 +249,7 @@ public class ApplicationEx extends Application
 
     @Override
     public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
+        try {
             switch (key) {
                 case "enabled":
                     ServiceSynchronize.reschedule(this);
@@ -289,6 +290,9 @@ public class ApplicationEx extends Application
                     Log.setLevel(this);
                     break;
             }
+        } catch (Throwable ex) {
+            Log.e(ex);
+        }
     }
 
     static void restart(Context context) {