Undefined services causes exception

[marcus-pousette]

• Version:
  0.45.0

Severity:

Low

Description:

Creating a libp2p instance with services that are undefined creates a null pointer exception even if it is allowed by the types

createLibp2p({
...,
    services: {
         abc: undefined
    }
})

To mitigate this I think there needs to be a null check before this

js-libp2p/src/libp2p.ts

Line 167 in 710da91

const service: any = createService(this.components)

to check if createService is a function.

I ended up with this error because I am generating different configs based on conditions, and this leads me to assign "undefined" to services relay occasionally

[achingbrain]

Related: #1573

[achingbrain]

A runtime check seems reasonable but this really shouldn't be allowed by the types.