deepMergeObject does not account for undefined property in recursion

[benjaminpreiss]

Hi! 👋

Firstly, thanks for your work on this project! 🙂

Today I used patch-package to patch magicast@0.2.4 for the project I'm working on.

When running

const requiredImports = `
import { browser } from "$app/environment"
import { initRootLayoutLoadWrapper } from "@inlang/sdk-js/adapter-sveltekit/shared"
import { initLocalStorageDetector, navigatorDetector } from "@inlang/sdk-js/detectors/client"
import { localStorageKey } from "@inlang/sdk-js/adapter-sveltekit/client/reactive"
`

const code = ''

const ast = parseModule(code)
const importsAst = parseModule(requiredImports)
deepMergeObject(ast, importsAst)

I get an error within deepMergeObject.
That's because the recursion happens to step into an undefined property.

Here is the diff that solved my problem:

diff --git a/node_modules/magicast/dist/helpers.cjs b/node_modules/magicast/dist/helpers.cjs
index 7813fd4..16d215a 100644
--- a/node_modules/magicast/dist/helpers.cjs
+++ b/node_modules/magicast/dist/helpers.cjs
@@ -8,7 +8,8 @@ require('@babel/parser');
 function deepMergeObject(magicast, object) {
   if (typeof object === "object") {
     for (const key in object) {
-      if (typeof object[key] === "object") {
+      if (typeof object[key] === "object" && magicast[key] !== undefined) {
+        // It could happen that magicast[key] is not defined
         deepMergeObject(magicast[key], object[key]);
       } else {
         magicast[key] = object[key];
diff --git a/node_modules/magicast/dist/helpers.mjs b/node_modules/magicast/dist/helpers.mjs
index 12c3234..fcb273c 100644
--- a/node_modules/magicast/dist/helpers.mjs
+++ b/node_modules/magicast/dist/helpers.mjs
@@ -6,7 +6,9 @@ import '@babel/parser';
 function deepMergeObject(magicast, object) {
   if (typeof object === "object") {
     for (const key in object) {
-      if (typeof object[key] === "object") {
+      if (typeof object[key] === "object" && magicast[key] !== undefined) {
+        // It could happen that magicast[key] is not defined
+        if(!magicast[key]) magicast[key] = {}
         deepMergeObject(magicast[key], object[key]);
       } else {
         magicast[key] = object[key];

This issue body was partially generated by patch-package.