refine tickets test

Co-authored-by: Jannis R <[email protected]>

test/e2e/db.js

@@ -58,7 +58,7 @@ const assertValidPrice = (t, p) => {
 }
 
 const assertValidTickets = (test, tickets) => {
-		test.ok(tickets);
+		test.ok(Array.isArray(tickets));
 		for (let fare of tickets) {
 			if (fare.name !== undefined) {
 				test.equal(typeof fare.name, 'string');