Golang best practices / error handling improvements

[ghost]

Description of the Change

Changed error messages to be more in line with Golang best practices:

• lower case first letters
• wrapping errors where appropriate

Benefits

Error messages are no longer silently dropped thanks to wrapping. Go developers will also be better equipped to deal with errors.

Possible Drawbacks

If users are relying on hard-coded error messages (which is a fundamentally bad idea) this change will break their implementation.

Verification Process

Ran mvn package successfully.