fix(overmind): return instance on transition to handle typing

Author: christianalfoni

packages/node_modules/overmind/src/statemachine.test.ts

@@ -208,7 +208,7 @@ describe('Statemachine', () => {
         FOO: ['BAR'],
         BAR: ['FOO']
       }, {
-        state: 'FOO'
+        state: 'FOO',
       })
     const transition: Action = async ({ state }) => {
       if (state.transition('BAR')) {
@@ -224,6 +224,8 @@ describe('Statemachine', () => {
       }
     }
 
+    
+
     const config = {
       state,
       actions: {

packages/node_modules/overmind/src/statemachine.ts

@@ -12,12 +12,12 @@ export type StatemachineTransitions<States extends TStates> = {
 
 export interface MachineMethods<States extends TStates> {
   matches<T extends States["state"]>(state: T): this is Statemachine<States, States extends {
-    state: T;
+    state: T
 } ? States : never>;
-  transition<State extends States["state"]>(
-    state: State,
-  ): this is Statemachine<States, States extends {
-    state: State
+  transition<T extends States["state"]>(
+    state: T,
+  ): undefined | Statemachine<States, States extends {
+    state: T
 } ? States : never>
 }
 
@@ -41,11 +41,10 @@ class StateMachine<States extends TStates, State extends TStates = States>  {
       tree.enableMutations()
       this.state = state
       Promise.resolve().then(() => tree.blockMutations())
-      return true
+      return this
     } else if (process.env.NODE_ENV === 'development') {
       console.warn(`Overmind Statemachine - You tried to transition into "${state}", but it is not a valid transition. The valid transitions are ${JSON.stringify(transitions[this.state])}`)
     }
-    return false
   }
   matches(state) {
     if (state === this.state) {