[release-19.0] Throttler: fix nil pointer dereference error (vitessio…

…#15180) (vitessio#15181)

Signed-off-by: Florent Poinsard <florent.poinsard@outlook.fr>
Signed-off-by: Vicent Marti <vmg@strn.cat>
Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Co-authored-by: Florent Poinsard <florent.poinsard@outlook.fr>
Co-authored-by: Vicent Marti <vmg@strn.cat>
Co-authored-by: vitess-bot[bot] <108069721+vitess-bot[bot]@users.noreply.github.com>
Co-authored-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>

go/vt/vttablet/tabletserver/throttle/throttler.go

@@ -772,7 +772,6 @@ func (throttler *Throttler) generateTabletProbeFunction(ctx context.Context, clu
 		req := &tabletmanagerdatapb.CheckThrottlerRequest{} // We leave AppName empty; it will default to VitessName anyway, and we can save some proto space
 		resp, gRPCErr := tmClient.CheckThrottler(ctx, probe.Tablet, req)
 		if gRPCErr != nil {
-			resp.StatusCode = http.StatusInternalServerError
 			mySQLThrottleMetric.Err = fmt.Errorf("gRPC error accessing tablet %v. Err=%v", probe.Alias, gRPCErr)
 			return mySQLThrottleMetric
 		}