Fix an issue about the categories/tags count.

[tsanie]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines.
• Tests for the changes have been added (for bug fixes / features).
  • Muse | Mist have been tested.
  • Pisces | Gemini have been tested.
• Docs have been added / updated (for bug fixes / features).

PR Type

What kind of change does this PR introduce?

• Bugfix.
• Feature.
• Code style update (formatting, local variables).
• Refactoring (no functional changes, no api changes).
• Build related changes.
• CI related changes.
• Documentation content changes.
• Other... Please describe:

What is the current behavior?

I have an article in the _drafts that contains 2 tags: compression, pngquant.
But the tags page shows the number with all articles including the draft ones.

• Screens like this:
  

What is the new behavior?

This commit changes the variable from reading site.tags.length to site.tags.filter(t => t.length).length, to make sure the result number will be right. (Also changes the categories)

But I'm not familiar with swig, so the single filter is splitted to 6 lines, so it looks like too verbose. 😒

• Screens with this changes:
  

Does this PR introduce a breaking change?

• Yes.
• No.

[ivan-nginx]

It's good, yeah. This bug is so old what i forget about it. GJ.

[ivan-nginx]

P.S. For Archives mb need to do the same thing.

[tsanie]

🎉 The Archives seems ok, site.posts will only returns posts which are published if we don't change the render_drafts to true.

[zhuzhuyule]

Good Fixed !

[youngjuning]

Good Fixed !

[jiangtj]

This is one of the reasons for the slow generation, maybe we can do it in scripts/merge-config.js.
Related issues #661 #539

[stevenjoezhang]

Superseded by hexojs/hexo#3624