Typescript: Property 'unaryCall' does not exist on type 'AbstractClientBase'

[GabrieleGervasiPEL]

Running protoc with grp-web plugin (1.4.2) generated a file *ServiceClientPb.ts. Such file contains a call to this.client_.unaryCall.
Meantime, npm module grp-web (1.4.2) doesn't contain such method in AbstractClientBase class.

Protoc configuration for plugin:
--grpc-web_out=import_style=typescript,mode=grpcweb