go/tendermint/keymanager: error Status() if keymanager doesn't exist

.changelog/2628.bugfix.md

@@ -0,0 +1,4 @@
+go/tendermint/keymanager: error in Status() if keymanager doesn't exist
+
+This fixes panics in the key-manager client if keymanager for the specific
+runtime doesn't exist.

go/consensus/tendermint/apps/keymanager/keymanager.go

@@ -96,21 +96,22 @@ func (app *keymanagerApplication) onEpochChange(ctx *abci.Context, epoch epochti
 
 		var forceEmit bool
 		oldStatus, err := state.Status(rt.ID)
-		if err != nil {
+		switch err {
+		case nil:
+		case api.ErrNoSuchStatus:
+			// This must be a new key manager runtime.
+			forceEmit = true
+			oldStatus = &api.Status{
+				ID: rt.ID,
+			}
+		default:
 			// This is fatal, as it suggests state corruption.
 			ctx.Logger().Error("failed to query key manager status",
 				"id", rt.ID,
 				"err", err,
 			)
 			return errors.Wrap(err, "failed to query key manager status")
 		}
-		if oldStatus == nil {
-			// This must be a new key manager runtime.
-			forceEmit = true
-			oldStatus = &api.Status{
-				ID: rt.ID,
-			}
-		}
 
 		newStatus := app.generateStatus(ctx, rt, oldStatus, nodes)
 		if forceEmit || !bytes.Equal(cbor.Marshal(oldStatus), cbor.Marshal(newStatus)) {

go/consensus/tendermint/apps/keymanager/state/state.go

@@ -60,7 +60,7 @@ func (st *ImmutableState) getStatusesRaw() ([][]byte, error) {
 func (st *ImmutableState) Status(id common.Namespace) (*api.Status, error) {
 	_, raw := st.Snapshot.Get(statusKeyFmt.Encode(&id))
 	if raw == nil {
-		return nil, nil
+		return nil, api.ErrNoSuchStatus
 	}
 
 	var status api.Status

go/keymanager/api/api.go

@@ -29,9 +29,9 @@ const (
 )
 
 var (
-	// ErrNoSuchKeyManager is the error returned when a key manager does not
+	// ErrNoSuchStatus is the error returned when a key manager status does not
 	// exist.
-	ErrNoSuchKeyManager = errors.New(ModuleName, 1, "keymanager: no such key manager")
+	ErrNoSuchStatus = errors.New(ModuleName, 1, "keymanager: no such status")
 
 	// TestPublicKey is the insecure hardcoded key manager public key, used
 	// in insecure builds when a RAK is unavailable.