fix: []byte nil resp

resp.go

@@ -556,6 +556,7 @@ type Marshaler interface {
 }
 
 // AppendAny appends any type to valid Redis type.
+//
 //	nil             -> null
 //	error           -> error (adds "ERR " when first word is not uppercase)
 //	string          -> bulk-string
@@ -583,7 +584,11 @@ func AppendAny(b []byte, v interface{}) []byte {
 	case string:
 		b = AppendBulkString(b, v)
 	case []byte:
+		if v == nil {
+			b = AppendNull(b)
+		} else {
 			b = AppendBulk(b, v)
+		}
 	case bool:
 		if v {
 			b = AppendBulkString(b, "1")