ws not working with empty get path when using prefix

[MomenNano]

🐛 Bug Report

when I register api module and give it a prefix option and then in the module file I can't set get route without any additional path name fastify.get('/', { websocket: true }, <function>)
and it gives me the error

AssertionError [ERR_ASSERTION]: Method 'GET' already declared for route '/api/'

it works when I add something to get path like fastify.get('/hi', { websocket: true }, <function>)
app.js

fastify.register(require('fastify-websocket'))

fastify.register(require('./api), { prefix: '/api' }

api.js

fastify.get('/', { websocket: true }, <function>)

Expected behavior

It should work in websocket. like it works fine without websocket (regular get '/' path)

Your Environment

• node version: 12
• fastify version: >=2.0.0
• os: Windows

[mcollina]

Would you like to send a Pull Request to address this issue? Remember to add unit tests.

[MomenNano]

I fixed it and I'll send a pull request