fix: expose Kraken errors in KrakenException message

[nyg]

Summary

KrakenException stored the errors returned by Kraken but never passed a message to RuntimeException, so getMessage() returned null. Tools that report exceptions through their message hid the actual error. For example, running EarnOverviewExample with a rejected API key made Maven print only null: KrakenException, and the underlying EAPI:Invalid key stayed hidden.

The constructor now sets the message to the errors joined with , , e.g. EAPI:Invalid key or EGeneral:Invalid arguments, EGeneral:Permission denied. For Funding (Beta) HTTP errors, the message is the status code followed by the response body. getErrors() is unchanged. A null error list, which Jackson produces when the envelope has no error field, still produces a null message instead of throwing a NullPointerException.

Testing

• New KrakenExceptionTest covers one error, several errors and a missing error list.
• mvnd -B clean verify passes: 597 tests.
• EarnOverviewExample run against the live API with an invalid key now fails with An exception occurred while executing the Java class. EAPI:Invalid key.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud