using my boilerplate yuh

@types/environment.d.ts

@@ -0,0 +1,22 @@
+declare global {
+    namespace NodeJS {
+        interface ProcessEnv {
+            NODE_ENV: 'development' | 'production';
+            CI?: string;
+            /** set this to make sure the extension id is the same for unpacked extensions
+             * @see https://developer.chrome.com/docs/apps/app_identity/#copy_key */
+            MANIFEST_KEY?: string;
+            /**
+             * The Node semantic versioning-compatible version of the extension. For preview-style releases, this variable
+             * converts versions like 1.0.0.100 to 1.0.0-beta.1.
+             */
+            SEMANTIC_VERSION?: string;
+        }
+    }
+
+    type Environment = typeof process.env.NODE_ENV;
+}
+
+// If this file has no import/export statements (i.e. is a script)
+// convert it into a module by adding an empty export statement.
+export {};