Improve error reporting

[alexander-akait]

• Operating System: any
• Node Version: any
• NPM Version: any
• webpack Version: any
• html-loader Version: 1

Feature Proposal

Suggestions:

• Report about invalid srcset
  • Starts with empty image-candidate string at ${input}
  • Empty image-candidate string at "${input}"
  • Ends with empty image-candidate string at "${input}"
• Using code frames for errors, it is allow to find errors easy.

Feature Use Case

Better DX

[Vi-50]

Check in test 2.0.0,3.0.0.