Enforce callback error handling

test/support/test-client.js

@@ -787,6 +787,10 @@ TestClient.prototype.getTile = function (z, x, y, params, callback) {
         function createLayergroup (err, templateId) {
             var next = this;
 
+            if (err) {
+                return next(err);
+            }
+
             if (layergroupId) {
                 return next(null, layergroupId);
             }

test/support/test-helper.js

@@ -160,6 +160,7 @@ function deleteRedisKeys (keysToDelete, callback) {
         var redisClient = redis.createClient(global.environment.redis.port);
         redisClient.select(keysToDelete[k], function () {
             redisClient.del(k, function (err, deletedKeysCount) {
+                assert.ifError(err);
                 redisClient.quit();
                 assert.notStrictEqual(deletedKeysCount, 0, 'No KEYS deleted for: [db=' + keysToDelete[k] + ']' + k);
                 taskDone(k);