Merge pull request #312 from josephschorr/backup-npe

Fix panic on backup call if the SpiceDB version is unsupported

internal/cmd/backup.go

@@ -74,6 +74,10 @@ func backupCmdFunc(cmd *cobra.Command, args []string) error {
 		hasProgressbar = true
 	}
 
+	if schemaResp.ReadAt == nil {
+		return fmt.Errorf("`backup` is not supported on this version of SpiceDB")
+	}
+
 	encoder, err := backupformat.NewEncoder(relWriter, schemaResp.SchemaText, schemaResp.ReadAt)
 	if err != nil {
 		return fmt.Errorf("error creating backup file encoder: %w", err)

pkg/backupformat/encoder.go

@@ -1,6 +1,7 @@
 package backupformat
 
 import (
+	"errors"
 	"fmt"
 	"io"
 
@@ -15,6 +16,10 @@ func NewEncoder(w io.Writer, schema string, token *v1.ZedToken) (*Encoder, error
 		return nil, fmt.Errorf("unable to create avro schema: %w", err)
 	}
 
+	if token == nil {
+		return nil, errors.New("missing expected token")
+	}
+
 	md := map[string][]byte{
 		metadataKeyZT: []byte(token.Token),
 	}