Throw if no top repos are found (#163)

Author: jakebailey

src/listTopRepos.ts

@@ -36,10 +36,13 @@ const skipRepos = [
 
 async function mainAsync() {
     const repos = await getPopularRepos(language, repoCount, repoStartIndex, skipRepos);
+    if (repos.length === 0) {
+        throw new Error("No repos found");
+    }
     await fs.promises.writeFile(outputPath, JSON.stringify(repos), { encoding: "utf-8" });
 }
 
 mainAsync().catch(err => {
     reportError(err, "Unhandled exception");
     process.exit(1);
-});
+});