Update index.ts

Author: XhmikosR

src/index.ts

@@ -62,7 +62,7 @@ function detective(src, options: detective.Options = { url: false }) {
     const files = nodes
       .filter((node) => isUrlNode(node))
       .map((node) => getValueOrUrl(node))
-      .filter((file): file is string => !!file);
+      .filter((file): file is string => Boolean(file));
 
     for (const file of files) {
       debug('found %s of %s', 'url() in declaration', file);