Empty AuthToken Causes Cryptic JWT Parse Error

[aniket866]

Describe the bug

Description

refreshAuthToken in pkg/connectors/microcks_client.go calls
jwt.ParseUnverified(configCtx.User.AuthToken, &claims) without first checking
whether AuthToken is empty. After a fresh install, after logout --token-only,
or whenever the config exists but contains no token, AuthToken is "". The JWT
parser returns an error for the empty string, which propagates all the way up to
NewClient and then to the user as a low-level JWT error rather than a
human-readable "please run microcks login" message.

// microcks_client.go (refreshAuthToken)
if c.RefreshToken == "" {
    return nil  // ← correctly handles empty refresh token
}
// ... but AuthToken="" is never guarded:
_, _, err = parser.ParseUnverified(configCtx.User.AuthToken, &claims)
if err != nil {
    return err  // ← surfaces as "token is malformed: ..." to the user
}

Ai Disclosure: No ai is used to code these lines,

Closes #551

[naitk2]

check code if err != nil {
return err // ← surfaces as "token is malformed: ..." to the user