Build fails if dest folder contains a README.md file

[pedrodim]

Bug report

Version

0.12.0

Steps to reproduce

Change the dest folder to something else on the root on the project.

module.exports = {
    dest: 'dist',
};

Add a READE.md file to .vuepress/public and launch the build task.
The first time everything will work just fine, you will have the new dest folder with all the files.
Launch the build task again and you will see a Error: Failed to compile with errors. error on the console.

Reproduction repo

What is expected?

Build to complete with no errors just as the first time it was launched, when no dest folder with the README.md existed on the project's root.

What is actually happening?

Probably vuepress is trying to parse the dest folder as a normal src folder instead of excluding it from parsing.

Also, the dest folder gets deleted after the script fails, maybe it should delete dest before parsing the files to compile?

Other relevant information

• Your OS: macOS 10.13.6
• Node.js version: v8.11.3
• Browser version: Chrome 67.0.3396.99
• Is this a global or local install? Local install
• Which package manager did you use for the install? NPM