feat(proxy-state-tree): allow force flushing

Author: christianalfoni

packages/node_modules/proxy-state-tree/src/index.ts

@@ -138,6 +138,16 @@ export class ProxyStateTree<T extends object> implements IProxyStateTree<T> {
     return () =>
       this.mutationCallbacks.splice(this.mutationCallbacks.indexOf(callback), 1)
   }
+  forceFlush() {
+    const emptyMutations = []
+    const emptyPaths = new Set()
+    for (let key in this.pathDependencies) {
+      const callbacks = this.pathDependencies[key]
+      callbacks.forEach((callback) => {
+        callback(emptyMutations, emptyPaths, this.currentFlushId++, false)
+      })
+    }
+  }
   flush(trees, isAsync: boolean = false) {
     let changes
     if (Array.isArray(trees)) {