diff --git a/.eslintrc.json b/.eslintrc.json
index 5612165..27ac580 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -38,7 +38,7 @@
         //     "setWithoutGet": true
         // }],
         // "block-scoped-var": "warn",
-        // "consistent-return": "error",
+        "consistent-return": "error",
         // "curly": "error",
         // "default-case": "warn",
 
diff --git a/scripts/preview-theme.js b/scripts/preview-theme.js
index 8e2f004..a668636 100644
--- a/scripts/preview-theme.js
+++ b/scripts/preview-theme.js
@@ -113,7 +113,7 @@ const isPreviewComment = (inputs, comment) => {
  * @param {string} owner Owner of the repository.
  * @param {string} repo Repository name.
  * @param {string} commenter Comment author.
- * @returns {Object} The GitHub comment object.
+ * @returns {Object | undefined} The GitHub comment object.
  */
 const findComment = async (octokit, issueNumber, owner, repo, commenter) => {
   const parameters = {
@@ -141,6 +141,8 @@ const findComment = async (octokit, issueNumber, owner, repo, commenter) => {
       debug(`No theme preview comment found.`);
     }
   }
+
+  return undefined;
 };
 
 /**
diff --git a/src/fetchers/repo-fetcher.js b/src/fetchers/repo-fetcher.js
index 75c3147..98e0a72 100644
--- a/src/fetchers/repo-fetcher.js
+++ b/src/fetchers/repo-fetcher.js
@@ -109,6 +109,8 @@ const fetchRepo = async (username, reponame) => {
       starCount: data.organization.repository.stargazers.totalCount,
     };
   }
+
+  throw new Error("Unexpected behavior");
 };
 
 export { fetchRepo };