"validator summary" requires validators

CHANGELOG.md

@@ -1,5 +1,5 @@
 dev:
-  - fix incorrect error when "deposit veirfy" is not given a withdrawal address
+  - fix incorrect error when "deposit verify" is not given a withdrawal address
   - allow truncated mnemonics (first four characters of each word)
   - add deneb information to "block info"
   - add epoch parameter to "validator yield"

cmd/validator/summary/process.go

@@ -27,6 +27,10 @@ import (
 )
 
 func (c *command) process(ctx context.Context) error {
+	if len(c.validators) == 0 {
+		return errors.New("no validators supplied")
+	}
+
 	// Obtain information we need to process.
 	err := c.setup(ctx)
 	if err != nil {