fix(proxy-state-tree): check for symbols on getter

Author: christianalfoni

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

@@ -71,6 +71,7 @@ function createArrayProxy(tree, value, path) {
     },
     set(target, prop, value) {
       const nestedPath = concat(path, prop)
+
       if (tree.status !== STATUS.TRACKING_MUTATIONS) {
         throw new Error(
           `proxy-state-tree - You are mutating the path "${nestedPath}", but it is not allowed`
@@ -92,6 +93,8 @@ function createObjectProxy(tree, value, path) {
     get(target, prop) {
       if (prop === IS_PROXY) return true
 
+      if (typeof prop === 'symbol') return target[prop]
+
       const value = target[prop]
       const nestedPath = concat(path, prop)