add valid method

fzf.go

@@ -26,11 +26,7 @@ func New(opts ...Option) (*FZF, error) {
 		opt(&o)
 	}
 
-	if o.limit < 1 {
-		return nil, errors.New("limit must be at least 1")
-	}
-
-	if err := o.inputPosition.Valid(); err != nil {
+	if err := o.valid(); err != nil {
 		return nil, err
 	}
 

option.go

@@ -1,6 +1,7 @@
 package fzf
 
 import (
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -109,6 +110,18 @@ type option struct {
 	hotReloadLocker sync.Locker
 }
 
+func (o *option) valid() error {
+	if o.limit < 1 {
+		return errors.New("limit must be at least 1")
+	}
+
+	if err := o.inputPosition.Valid(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func (o *option) multiple() bool {
 	return o.noLimit || o.limit > 1
 }