The url configuration should be verified

[ShaytonXu]

Check List

• I have already read Docs page.
• I have already searched existing issues.

Feature Request

I have a old hexo source blog(hexo@3.x), and I try to upgrade to the latest hexo version, but when I run hexo server, I got the error:

Template render error: (unknown path)
  TypeError: Invalid URL

And finally I found the source of error is the new URL in asset_img processor.

And it's occured because my url config was not started with https. This took me some time to figure this out. But I think this error can be found when valid the config file.

Others

No response

[ShaytonXu]

I just create a pull request, I think it may help.

#5578