The only value that ErrorHandler::GetErrorString() adds over
ErrorStringFactory::CreateString() is that it will delete the pInfo a
2nd time, because the ErrorInfo::GetErrorInfo() returns the same object
twice.

This may fix it, but it's generally hard to tell what this
brain damaged error handling code will do.

(regression from 1167df7d)

Change-Id: I22f446bee669cae8c5288bcc2f1e1d0299f5b384