Empty Code Block not processed by theme component

[lebalz]

Have you read the Contributing Guidelines on issues?

• I have read the Contributing Guidelines on issues.

Prerequisites

• I'm using the latest version of Docusaurus.
• I have tried the npm run clear or yarn clear command.
• I have tried rm -rf node_modules yarn.lock package-lock.json and re-installing packages.
• I have tried creating a repro with https://new.docusaurus.io.
• I have read the console error message carefully (if applicable).

Description

When using an empty Codeblock (e.g. for a live react playground, that does not have any default code), the code is shown as inline-code instead of a code-block. Therefore the theme-live-codeblock is not applied to this codeblock and the expected "live"-behaviour is not available.

The repro only shows the minimal case, where a normal empty codeblock is displayed as an inline code.

Reproducible demo

👉 https://codesandbox.io and checkout /docs/intro

Steps to reproduce

Add an empty codeblock inside a markdown document:

```
```

Expected behavior

The result shall be a codeblock:

Actual behavior

An inline codeblock is displayed instead

(Adding an empty line to the codeblock does not fix the issue)

Your environment

• Public source code: 👉 codesandbox.io at #/docs/intro
• Docusaurus version used: 3.0.1
• Environment name and version (e.g. Chrome 89, Node.js 16.4): Microsoft Edge Version 120.0.2210.91 (Offizielles Build) (64-Bit)
• Operating system and version (e.g. Ubuntu 20.04.2 LTS): Windows 11

Self-service

• I'd be willing to fix this bug myself.