Allow scanning to nil as no-op

pgtype.go

@@ -833,6 +833,10 @@ func (ci *ConnInfo) PlanScan(oid uint32, formatCode int16, buf []byte, dst inter
 }
 
 func (ci *ConnInfo) Scan(oid uint32, formatCode int16, src []byte, dst interface{}) error {
+	if dst == nil {
+		return nil
+	}
+
 	plan := ci.PlanScan(oid, formatCode, src, dst)
 	return plan.Scan(ci, oid, formatCode, src, dst)
 }

pgtype_test.go

@@ -64,6 +64,13 @@ func TestConnInfoParamFormatCodeForOID(t *testing.T) {
 	assert.Equal(t, int16(pgtype.BinaryFormatCode), ci.ParamFormatCodeForOID(pgtype.Int4OID))
 }
 
+func TestConnInfoScanNilIsNoOp(t *testing.T) {
+	ci := pgtype.NewConnInfo()
+
+	err := ci.Scan(pgtype.TextOID, pgx.TextFormatCode, []byte("foo"), nil)
+	assert.NoError(t, err)
+}
+
 func TestConnInfoScanUnknownOIDToStringsAndBytes(t *testing.T) {
 	unknownOID := uint32(999999)
 	srcBuf := []byte("foo")