fix(overmind): typing issue with statemachine transitions

Author: christianalfoni

packages/node_modules/overmind/src/statemachine.ts

@@ -1,7 +1,5 @@
 import { PROXY_TREE, VALUE } from 'proxy-state-tree'
 
-import { Derive } from './'
-
 export type StatemachineDefinition<States extends string> = {
   initial: States,
   states: {
@@ -13,7 +11,7 @@ export type Statemachine<States extends string> = {
   current: States
   reset: () => void
 } & {
-  [State in States]: <T>(entry?: () => T, exit?: () => void) => T
+  [State in States]: <T extends () => any>(entry?: T, exit?: () => void) => T extends () => infer U ? U : void
 }
 
 const CURRENT_EXIT = Symbol('CURRENT_EXIT')