fix(overmind): change to method to grab mutationtree in production

Author: christianalfoni

packages/node_modules/overmind/src/index.ts

@@ -138,15 +138,15 @@ export class Overmind<Config extends Configuration> implements Configuration {
 
     if (IS_PRODUCTION) {
       eventHub.on(EventType.OPERATOR_ASYNC, () => {
-        proxyStateTree.mutationTree.flush()
+        proxyStateTree.getMutationTree().flush()
       })
       eventHub.on(EventType.ACTION_END, () => {
-        proxyStateTree.mutationTree.flush()
+        proxyStateTree.getMutationTree().flush()
       })
 
       let nextTick
       const flushTree = () => {
-        proxyStateTree.mutationTree.flush(true)
+        proxyStateTree.getMutationTree().flush(true)
       }
 
       this.proxyStateTree.onMutation(() => {
@@ -201,7 +201,7 @@ export class Overmind<Config extends Configuration> implements Configuration {
     if (IS_PRODUCTION) {
       return {
         getMutationTree: () => {
-          return this.proxyStateTree.mutationTree
+          return this.proxyStateTree.getMutationTree()
         },
       } as Execution
     }