diff --git a/src/app/components/HomePage/Masthead.tsx b/src/app/components/HomePage/Masthead.tsx
index 668dd7dc..b01e51ee 100644
--- a/src/app/components/HomePage/Masthead.tsx
+++ b/src/app/components/HomePage/Masthead.tsx
@@ -19,7 +19,7 @@ export function Masthead() {
         >
           React Boilerplate
         </A>{' '}
-        as{' '}
+        as a{' '}
         <A
           href="https://github.com/facebook/create-react-app"
           target="_blank"
diff --git a/src/app/containers/GithubRepoForm/index.tsx b/src/app/containers/GithubRepoForm/index.tsx
index f7bb17b9..131a95dc 100644
--- a/src/app/containers/GithubRepoForm/index.tsx
+++ b/src/app/containers/GithubRepoForm/index.tsx
@@ -79,7 +79,7 @@ export function GithubRepoForm() {
           ))}
         </List>
       ) : error ? (
-        <ErrorText>There is an error occurred!</ErrorText>
+        <ErrorText>Oops! An error has occurred</ErrorText>
       ) : null}
     </Wrapper>
   );
diff --git a/src/styles/theme/utils.ts b/src/styles/theme/utils.ts
index 9614052e..f087ad5e 100644
--- a/src/styles/theme/utils.ts
+++ b/src/styles/theme/utils.ts
@@ -1,7 +1,8 @@
 import { ThemeKeyType } from './types';
 
-export const isSysyemDark = window.matchMedia('(prefers-color-scheme: dark)')
-  .matches;
+export const isSysyemDark = window.matchMedia
+  ? window.matchMedia('(prefers-color-scheme: dark)')?.matches
+  : undefined;
 
 export function saveTheme(theme: ThemeKeyType) {
   if (window.localStorage) {