fix(key): Unbound keys should be disabled

* fix condition for #188
This is a fix of https://github.com/charmbracelet/bubbles/pull/188
Unbound keys has nil keys and they are not Enabled

key/key.go

@@ -106,7 +106,7 @@ func (b Binding) Help() Help {
 // keybindings won't be activated and won't show up in help. Keybindings are
 // enabled by default.
 func (b Binding) Enabled() bool {
-	return !b.disabled || b.keys == nil
+	return !b.disabled && b.keys != nil
 }
 
 // SetEnabled enables or disables the keybinding.

key/key_test.go

@@ -0,0 +1,26 @@
+package key
+
+import (
+	"testing"
+)
+
+func TestBinding_Enabled(t *testing.T) {
+	binding := NewBinding(
+		WithKeys("k", "up"),
+		WithHelp("↑/k", "move up"),
+	)
+	if !binding.Enabled() {
+		t.Errorf("expected key to be Enabled")
+	}
+
+	binding.SetEnabled(false)
+	if binding.Enabled() {
+		t.Errorf("expected key not to be Enabled")
+	}
+
+	binding.SetEnabled(true)
+	binding.Unbind()
+	if binding.Enabled() {
+		t.Errorf("expected key not to be Enabled")
+	}
+}