diff --git a/ext/bin/build.js b/ext/bin/build.js
index e91d045..0e7af3e 100644
--- a/ext/bin/build.js
+++ b/ext/bin/build.js
@@ -102,7 +102,7 @@ if (argv.mode === "production") {
 /**
  * Handle build results.
  *
- * @param {esbuild.BuildResult} result
+ * @param {esbuild.BuildResult | null} result
  */
 function onBuildResult(result) {
     if (result?.errors.length) {
diff --git a/ext/bin/lib/copyFilesPlugin.js b/ext/bin/lib/copyFilesPlugin.js
index f6b22ea..7e68cf5 100644
--- a/ext/bin/lib/copyFilesPlugin.js
+++ b/ext/bin/lib/copyFilesPlugin.js
@@ -14,7 +14,7 @@ const esbuild = require("esbuild");
 function* walk(rootPath) {
     const pathsToWalk = [rootPath];
     while (pathsToWalk.length > 0) {
-        const currentPath = pathsToWalk.pop();
+        const currentPath = /** @type {string} */ (pathsToWalk.pop());
         if (fs.statSync(currentPath).isFile()) {
             yield currentPath;
         } else {