Issue with erasing `B` from the context and runtime error

import { Context, Effect } from 'effect'

interface A {
  a: 'a'
}

export const A = Context.Tag<A>()

interface B {
  a: 'a'
  b: 'b'
}

export const B = Context.Tag<B>()

const program = Effect.map(B, b => b.b)

const runnable = Effect.provideService(
  program,
  A,
  A.of({ a: 'a' }),
)

Effect.runPromise(runnable)