[@0xsequence/multicall] Typescript error: Class 'MulticallExternalProvider' incorrectly implements interface 'ExternalProvider'

[Spenhouet]

I'm building a node.js + Typescript application with @0xsequence/multicall as dependency and the build throws this error:

node_modules/@0xsequence/multicall/dist/declarations/src/providers/external-provider.d.ts:4:22 - error TS2420: 
Class 'MulticallExternalProvider' incorrectly implements interface 'ExternalProvider'.
  Types of property 'isMetaMask' are incompatible.
    Type 'boolean | undefined' is not assignable to type 'boolean'.
      Type 'undefined' is not assignable to type 'boolean'.