handle not found errors for organizations

[szabgab]

Some of the organizations return a json that contains

{"message": "Not Found", "documentation_url": "https://docs.github.com/rest/reference/orgs#get-an-organization"}

Currently we disregard this message.

• Are there typos in the names?
• Are these users (and not github organizations)?
• In any case the code should report these problems.

[szabgab]

Some were typos, some were personal accounts.

We need to have some indication for personal account on the web site.