linking marked-up text generates multiple `<a>` tags

Example text, where "BOLD" is _bolded_:

`one BOLD two`

Selecting this text and adding a link to it will generate HTML with 3 `<a>` tags, e.g.:

```
<a href="...">one </a><strong><a href='...'>BOLD</a></strong><a href='...'> two</a>
```

The rendered HTML should be:

```
<a href="...">one <strong>BOLD</strong> two</a>
```

This can interfere with styling and is not great for SEO.
