fix: cmd+w fails to close window with only one tab

Regression from 9254

Author: starpit

plugins/plugin-core-support/src/lib/cmds/quit.ts

@@ -22,5 +22,11 @@
 import type { Arguments, Registrar } from '@kui-shell/core'
 
 export default (commandTree: Registrar) => {
+  // register a window close command handler
+  commandTree.listen('/window/close', () => {
+    window.close()
+    return true
+  })
+
   commandTree.listen('/exit', ({ REPL }: Arguments) => REPL.qexec('tab close'))
 }