(markdown) Images with empty alt or links with empty text do not have highlight

[yrccondor]

Describe the issue
Images with empty alt or links with empty text do not have highlight

Which language seems to have the issue?
markdown

Are you using highlight or highlightAuto?
highlight

Sample Code to Reproduce

![](https://example.com)

![alt](https://example.com)

[](https://example.com)

[text](https://example.com)

gives out HTML result

![](https://example.com)

![<span class="hljs-string">alt</span>](<span class="hljs-link">https://example.com</span>)

[](https://example.com)

[<span class="hljs-string">text</span>](<span class="hljs-link">https://example.com</span>)

Expected behavior

![](<span class="hljs-link">https://example.com</span>)

![<span class="hljs-string">alt</span>](<span class="hljs-link">https://example.com</span>)

[](<span class="hljs-link">https://example.com</span>)

[<span class="hljs-string">text</span>](<span class="hljs-link">https://example.com</span>)

Additional context

highlight.js/src/languages/markdown.js

Lines 88 to 110 in 9350caf

	{
	begin: /\[.+?\]\[.*?\]/,
	relevance: 0
	},
	// popular internet URLs
	{
	begin: /\[.+?\]\(((data|javascript|mailto):|(?:http|ftp)s?:\/\/).*?\)/,
	relevance: 2
	},
	{
	begin: regex.concat(/\[.+?\]\(/, URL_SCHEME, /:\/\/.*?\)/),
	relevance: 2
	},
	// relative urls
	{
	begin: /\[.+?\]\([./?&#].*?\)/,
	relevance: 1
	},
	// whatever else, lower relevance (might not be a link at all)
	{
	begin: /\[.+?\]\(.*?\)/,
	relevance: 0
	}

Looks like it will only match square brackets with something in between.