WriteAPIBlocking discards http2.Error content

[pabigot]

The fixes for issue #235 included:

influxdb-client-go/api/writeAPIBlocking.go

Lines 76 to 78 in 4218b50

	if err != nil {
	return err.Unwrap()
	}

which unwraps the error returned from the lower levels.

When the error is an http2.Error, e.g. because the token is unauthorized, this invokes:

influxdb-client-go/api/http/error.go

Lines 34 to 36 in 4218b50

	func (e *Error) Unwrap() error {
	return errors.New(e.Error())
	}

which completely discards all the Influx-specific information, producing an error of type errors.errorString that has nothing but the text.

So, unlike the non-blocking API, an error from WriteAPIBlocking() does not return an http2.Error, making it complex to understand why the write failed. The idiom proposed in #292 (comment) cannot recover the lost information.