Merge pull request vitessio#5735 from planetscale/jacques_5734

Address vitessio#5734 by forming MySQL error packet on query parse error during

go/mysql/conn.go

@@ -853,7 +853,12 @@ func (c *Conn) handleNextCommand(handler Handler) error {
 
  statement, err := sqlparser.ParseStrictDDL(query)
  if err != nil {
- return err
+ log.Errorf("Conn %v: Error parsing prepared statement: %v", c, err)
+ if werr := c.writeErrorPacketFromError(err); werr != nil {
+ // If we can't even write the error, we're done.
+ log.Errorf("Conn %v: Error writing prepared statement error: %v", c, werr)
+ return werr
+ }
  }
 
  paramsCount := uint16(0)