fix the errno extraction for the scatter errors as warnings feature
fix the errno extraction for the scatter errors as warnings feature

Need to call NewSQLErrorFromError to parse the errno out of the
message since it isn't necessarily a SQLError.

Signed-off-by: Michael Demmer <4b836671cce77b1b2fbe63e5b2a1661879d8af44@slack-corp.com>

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