fix: handle errors appended to body by mermaid

[JoshStern]

Overview

• Removes unused out div.
• If the svg appended by mermaid is still on the page then move it to the correct location and cleanup the wrapper.

For some errors the div + svg added by mermaid is not cleaned up and an error is thrown here. This leads to a list of permanent error messages that grows until the preview is refreshed.

Repro Steps

Open a markdown document with the following content:

```mermaid
flowchart

Add and remove newlines and the error svgs will grow. There is also no error info.

<img width="738" alt="image" src="https://user-images.githubusercontent.com/10948202/222986263-e4a3bb9a-bb14-4b74-b975-c0bd796f5d68.png">
<img width="446" alt="image" src="https://user-images.githubusercontent.com/10948202/222986315-a7f2f8ee-7ff6-4941-a0b5-c0f8f6971dac.png">

## After fix
Errors should not grow, and fully disappear when resolved.

<img width="480" alt="image" src="https://user-images.githubusercontent.com/10948202/222986362-9ec9a9de-f094-41ef-8eee-bd827a684da8.png">

Thank you for putting this extension together! It's been super useful.

[mjbvz]

Thanks!

[mjbvz]

Published as 1.17.6