add fsused to block_devices output

src/routes/system.js

@@ -170,7 +170,7 @@ async function getFilesystems(req, res, next) {
 }
 
 async function getFilesystemUsage(req, res, next) {
-    if (typeof req.query.filesystem !== 'string') return next(new HttpError(400, 'getFilesystemUsage'));
+    if (typeof req.query.filesystem !== 'string') return next(new HttpError(400, 'Missing filesystem query param'));
     if (req.headers.accept !== 'text/event-stream') return next(new HttpError(400, 'This API call requires EventStream'));
 
     const [error, task] = await safe(system.getFilesystemUsage(req.query.filesystem));