Fix long first lines causing hanging (#41)

Author: Nixinova

changelog.md

@@ -1,5 +1,8 @@
 # Changelog
 
+## Next
+- Fixed files with long first lines causing lag ([#41](https://github.com/Nixinova/LinguistJS/issues/41)).
+
 ## 2.9.1
 *2025-04-04*
 - Added CLI error message when passing invalid category input.

src/helpers/read-file.ts

@@ -10,7 +10,7 @@ export default async function readFileChunk(filename: string, onlyFirstLine: boo
 	let content = '';
 	for await (const data of stream) { // may throw
 		content += data.toString();
-		if (onlyFirstLine && content.includes('\n')) {
+		if (onlyFirstLine) {
 			return content.split(/\r?\n/)[0];
 		}
 	}