kvserver: improve reporting for an assertion

Downgrade the assertion to returning an error to the user, asking nicely
for providing their repro on the issue. We keep reporting to sentry
despite not terminating the process.

Touches cockroachdb#46652.

Release justification: low-risk reporting improvement
Release note: None

pkg/kv/kvserver/replica_evaluate.go

@@ -21,6 +21,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
 	"github.com/cockroachdb/cockroach/pkg/storage"
 	"github.com/cockroachdb/cockroach/pkg/storage/enginepb"
+	"github.com/cockroachdb/cockroach/pkg/util/errorutil"
 	"github.com/cockroachdb/cockroach/pkg/util/hlc"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/errors"
@@ -333,7 +334,14 @@ func evaluateBatch(
 		if limit := baHeader.MaxSpanRequestKeys; limit > 0 {
 			retResults := reply.Header().NumKeys
 			if retResults > limit {
-				log.Fatalf(ctx, "received %d results, limit was %d", retResults, limit)
+				index, retResults, limit := index, retResults, limit // don't alloc unless branch taken
+				err := errorutil.UnexpectedWithIssueErrorf(46652,
+					"received %d results, limit was %d (original limit: %d, batch=%s idx=%d)",
+					errors.Safe(retResults), errors.Safe(limit),
+					errors.Safe(ba.Header.MaxSpanRequestKeys),
+					errors.Safe(ba.Summary()), errors.Safe(index))
+				errorutil.SendReport(ctx, &rec.ClusterSettings().SV, err)
+				return nil, mergedResult, roachpb.NewError(err)
 			} else if retResults < limit {
 				baHeader.MaxSpanRequestKeys -= retResults
 			} else {