Added logging

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

@@ -149,6 +149,7 @@ public class Helper {
             try {
                 customTabsIntent.launchUrl(context, uri);
             } catch (ActivityNotFoundException ex) {
+                Log.w(ex);
                 Toast.makeText(context, context.getString(R.string.title_no_viewer, uri.toString()), Toast.LENGTH_LONG).show();
             } catch (Throwable ex) {
                 Log.e(ex);