修复ProgressDialog的出现时机

[Richasy]

Close

在文件转移过快时，progressDialog还没出现就已经转移完毕，这种情况下会报错

PR type

What is the purpose of this PR?

• Bug fix

What is the current behavior?

在文件转移过快时，progressDialog还没出现就已经转移完毕，这种情况下会报错

What is the new behavior?

加了个判断条件以避免这种情况发生

PR checklist

Please check that your PR meets the following requirements:

• [x] App successfully launched
• [x] File headers have been added to all source files
• [x] NOT Contains breaking updates

Remark

更新了一下epub库