logs: use %o to format error

otherwise, they are printed as multi-line and this messes up tail+date formatting

src/updater.js

@@ -200,7 +200,7 @@ async function updateToLatest(options, auditSource) {
     tasks.startTask(taskId, { timeout: 20 * 60 * 60 * 1000 /* 20 hours */, nice: 15, memoryLimit }, async (error) => {
         locker.unlock(locker.OP_BOX_UPDATE);
 
-        debug('Update failed with error', error);
+        debug('Update failed with error. %o', error);
 
         const timedOut = error.code === tasks.ETIMEOUT;
         await safe(eventlog.add(eventlog.ACTION_UPDATE_FINISH, auditSource, { taskId, errorMessage: error.message, timedOut }));