fix: the process not found on Windows

src/index.ts

@@ -35,10 +35,26 @@ export const defineConfig = (
       ) => MaybePromise<Options | Options[]>)
 ) => options
 
+/**
+ * tree-kill use `taskkill` command on Windows to kill the process,
+ * it may return 128 as exit code when the process has already exited.
+ * @see https://github.com/egoist/tsup/issues/976
+ */
+const isTaskkillCmdProcessNotFoundError = (err: Error) => {
+  return (
+    process.platform === 'win32' &&
+    'cmd' in err &&
+    'code' in err &&
+    typeof err.cmd === 'string' &&
+    err.cmd.startsWith('taskkill') &&
+    err.code === 128
+  )
+}
+
 const killProcess = ({ pid, signal }: { pid: number; signal: KILL_SIGNAL }) =>
   new Promise<void>((resolve, reject) => {
     kill(pid, signal, (err) => {
-      if (err) return reject(err)
+      if (err && !isTaskkillCmdProcessNotFoundError(err)) return reject(err)
       resolve()
     })
   })