Highlighting more than 2 separate lines when importing code snippets produces "Invalid code snippet option" error

[adamdehaven]

• I confirm that this is an issue rather than a question.

Bug report

Steps to reproduce

1. Save a new code snippet to .vuepress/public/snippet.js with any content. Here's an example:

const name = 'First Last'

// Create person object
let person = {
    name: name,
    email: 'test@example.com'
}

2. Import code snippet in a Markdown file with lines highlighted: <<< @/.vuepress/public/snippet.js{2-4,6}
3. Serve project locally with npm run dev (or whatever your serve command is to run vuepress dev)
4. See error message: "Invalid code snippet option"

What is expected?

Code should be imported with highlighted lines.

What is actually happening?

Code import fails with message:

Invalid code snippet option

Examples:

• <<< @/.vuepress/public/snippet.js - ✔️ Works (no highlighted lines)
• <<< @/.vuepress/public/snippet.js{2} - ✔️ Works (1 highlighted line)
• <<< @/.vuepress/public/snippet.js{2,4} - ✔️ Works (2 highlighted lines)
• <<< @/.vuepress/public/snippet.js{2-4} - ✔️ Works (1 range of highlighted lines)
• <<< @/.vuepress/public/snippet.js{2,4,6} - ❌ Fails (3 highlighted lines)
• <<< @/.vuepress/public/snippet.js{2-4,6} - ❌ Fails (1 range of highlighted lines and 1 single line)

Other relevant information

• Code highlighting works property in regular code blocks
• Output of npx vuepress info in my VuePress project:

Environment Info:

  System:
    OS: Windows 10 10.0.16299
    CPU: (8) x64 Intel(R) Core(TM) i5-8350U CPU @ 1.70GHz
  Binaries:
    Node: 10.15.1 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.0 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 6.13.4 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: 41.16299.1480.0
  npmPackages:
    @vuepress/core:  1.5.2
    @vuepress/theme-default:  1.5.2
    vuepress: ^1.5.2 => 1.5.2
  npmGlobalPackages:
    vuepress: Not Found

[adamdehaven]

Fixed with #2441