message: expose fiberContext
diff: @@ -11,7 +11,6 @@ import { flatten as exitFlatten } from "../Exit/core"
  import type { Exit } from "../Exit/exit"
  // fiber
  import { FiberContext } from "../Fiber/context"
  -import type { Runtime as FiberRuntime } from "../Fiber/core"
  import { interruptible } from "../Fiber/core"
  import { newFiberId } from "../Fiber/id"
  import { Platform } from "../Fiber/platform"
  @@ -122,7 +121,7 @@ export class CustomRuntime<R, X> {
  )
  }
  - runFiber<E, A>(self: Effect<R, E, A>): FiberRuntime<E, A> {
  + runFiber<E, A>(self: Effect<R, E, A>): FiberContext<E, A> {
  const context = this.fiberContext<E, A>(self)
  context.evaluateLater(self[_I])
  return context
  