Leave the page when entering a spoiler hint without a hidden message and pressing the ENTER key

[joudinet]

Describe the bug In my configuration, the chat is running in the following URL: https://example.com/?chat When using incorrectly the spoiler toolbar button by typing a spoiler hint and pressing the ENTER key (so with an empty hidden message), it leaves the page and goes to https://example.com/?

To Reproduce Steps to reproduce the behavior:

1. Configure your application to run conversejs v9.1.1 on https://example.com/?chat so it automatically join a MUC room (see converse configuration below).
2. Click on the spoiler toolbar button.
3. Enter a spoiler hint and press the ENTER key (so the hidden message is empty).
4. See error

Expected behavior I expect to not do anything when I press the ENTER key, like when you click on the send button.

Environment (please complete the following information):

• Desktop and Mobile
• All browsers I tested with [Chrome, Firefox, Edge, Safari]
• Converse.js version: 9.1.1

Additional context See the converse configuration I use if it may help to reproduce the bug:

        "allow_contact_requests": false,
        "allow_logout": false,
        "allow_muc_invitations": false,
        "allow_user_trust_override": "off",
        "assets_path": "/conversejs/",
        "authentication": "anonymous",
        "auto_login": true,
        "auto_join_rooms": [ "[email protected]" ],
        "clear_cache_on_logout": true,
        "discover_connection_methods": false,
        "enable_smacks": false,
        "hide_muc_server": true,
        "jid": "example.com",
        "keepalive": false,
        "locked_muc_nickname": true,
        "message_archiving": "never",
        "muc_disable_slash_commands": true,
        "notify_all_room_messages": [ "[email protected]" ],
        "persistent_store": "sessionStorage",
        "play_sounds": true,
        "sounds_path": "/conversejs/sounds/",
        "strict_plugin_dependencies": false,
        "singleton": true,
        "view_mode": "embedded",
        "websocket_url": "wss://server-1.example.com/ws/"