Remove empty strings from button_text before adding buttons

src/core/hle/applets/swkbd.cpp

@@ -201,6 +201,7 @@ Frontend::KeyboardConfig SoftwareKeyboard::ToFrontendConfig(
                      });
     if (frontend_config.has_custom_button_text) {
         for (const auto& text : config.button_text) {
+            if (text.front() != 0)
                 frontend_config.button_text.push_back(Common::UTF16BufferToUTF8(text));
         }
     }