Fix a bug where you cannot unset the default --nth using change-nth

CHANGELOG.md

@@ -4,6 +4,7 @@ CHANGELOG
 0.65.1
 ------
 - Fixed incorrect `$FZF_CLICK_HEADER_WORD` and `$FZF_CLICK_FOOTER_WORD` when the header or footer contains ANSI escape sequences and tab characters.
+- Fixed a bug where you cannot unset the default `--nth` using `change-nth` action.
 
 0.65.0
 ------

src/terminal.go

@@ -5726,7 +5726,7 @@ func (t *Terminal) Loop() error {
 				capture(true, func(expr string) {
 					// Split nth expression
 					tokens := strings.Split(expr, "|")
-					if nth, err := splitNth(tokens[0]); err == nil {
+					if nth, err := splitNth(tokens[0]); err == nil || len(expr) == 0 {
 						// Changed
 						newNth = &nth
 					} else {

test/test_core.rb

@@ -2045,4 +2045,19 @@ class TestCore < TestInteractive
     tmux.send_keys :b
     tmux.until { |lines| assert_includes lines, '> 9' }
   end
+
+  def test_change_nth_unset_default
+    tmux.send_keys %(echo foo bar | #{FZF} --nth 2 --query fb --bind space:change-nth:), :Enter
+    tmux.until do
+      assert_equal 1, it.item_count
+      assert_equal 0, it.match_count
+    end
+
+    tmux.send_keys :Space
+
+    tmux.until do
+      assert_equal 1, it.item_count
+      assert_equal 1, it.match_count
+    end
+  end
 end