fix: Improve error message for scanning an image that doesn't exist

[ahmed-agabani-snyk]

• Ready for review
• Follows CONTRIBUTING rules
• Reviewed by Snyk internal team

What does this PR do?

Converts an internal error into an actionable human readable message.

How should this be manually tested?

• snyk container monitor doesnotexist
• snyk container test doesnotexist

What are the relevant tickets?

• JIRA: DC-948

Screenshots

[github-actions]

Expected release notes (by @ahmed-agabani-snyk)

fixes:
Improve error message for scanning an image that doesn't exist (a5ccb25)

• I hereby acknowledge these release notes are 🥙 AWESOME 🥙

[yaronschwimmer]

I think this can also be a login (to docker hub) issue, and not necessarily the image not existing. maybe we need to rephrase?

[ahmed-agabani-snyk]

tl;dr:
Product decided on Failed to scan image "<image-name>". Please make sure the image and/or repository exist.

Product's rationale:

The thinking was not to overload information (so removed the auth part) + make it actionable enough (so they'll check whether it exists)

Personal thoughts:
As an engineer, the first thing I would do if I see this message is to run docker pull <image-name> to check if it exists. Docker will provide a more detailed error.

I do not think it should be the Snyk CLI's responsibility to accurately diagnose a problem with docker.

History:

• current message snyk cli provides: authentication required
• current message docker cli provides: Error response from daemon: pull access denied for doesnotexist, repository does not exist or may require 'docker login': denied: requested access to the resource is denied
• message I used when developing this fix:
  Pull access denied for 'doesnotexist', repository does not exist or may require 'docker login'

[snyksec]

🎉 This PR is included in version 1.424.3 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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