diff --git a/src/platforms/GitHub/DOMHelper.ts b/src/platforms/GitHub/DOMHelper.ts
index dc42fce..adb2a81 100644
--- a/src/platforms/GitHub/DOMHelper.ts
+++ b/src/platforms/GitHub/DOMHelper.ts
@@ -7,8 +7,8 @@ import { CopyFileButton, copyFileButtonClassName } from './CopyFileButton'
 
 export function resolveMeta(): Partial<MetaData> {
   const metaData = {
-    userName: $('[itemprop="author"] > a[rel="author"]', e => e.textContent?.trim()),
-    repoName: $('[itemprop="name"] > a[href]', e => e.textContent?.trim()),
+    userName: $('[itemprop="author"] > a[rel="author"]', e => e.textContent?.trim()) || undefined,
+    repoName: $('[itemprop="name"] > a[href]', e => e.textContent?.trim()) || undefined,
     branchName: getCurrentBranch(true),
   }
   if (!metaData.userName || !metaData.repoName) {
@@ -65,7 +65,7 @@ export function getCurrentBranch(passive = false) {
 
   const findFileButtonSelector =
     '#js-repo-pjax-container .repository-content .file-navigation a[data-hotkey="t"]'
-  const urlFromFindFileButton: string | undefined = $(
+  const urlFromFindFileButton = $(
     findFileButtonSelector,
     element => (element as HTMLAnchorElement).href,
   )
diff --git a/src/utils/DOMHelper.ts b/src/utils/DOMHelper.ts
index 301560a..be14b24 100644
--- a/src/utils/DOMHelper.ts
+++ b/src/utils/DOMHelper.ts
@@ -38,17 +38,17 @@ export function setBodyIndent(shouldShowGitako: boolean) {
 }
 
 export function $(selector: string): HTMLElement | null
-export function $<T1>(selector: string, existCallback: (element: HTMLElement) => T1): T1
+export function $<T1>(selector: string, existCallback: (element: HTMLElement) => T1): T1 | null
 export function $<T1, T2>(
   selector: string,
   existCallback: (element: HTMLElement) => T1,
   otherwise: () => T2,
-): T1 | T2
+): T1 | T2 | null
 export function $<T2>(
   selector: string,
   existCallback: undefined | null,
   otherwise: () => T2,
-): HTMLElement | null | T2
+): HTMLElement | T2 | null
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export function $(selector: string, existCallback?: any, otherwise?: any) {
   const element = document.querySelector(selector)