[Fix] utils.merge: avoid a crash with a null target and an array source

Author: ljharb

test/utils.js

@@ -6,6 +6,8 @@ var utils = require('../lib/utils');
 test('merge()', function (t) {
     t.deepEqual(utils.merge(null, true), [null, true], 'merges true into null');
 
+    t.deepEqual(utils.merge(null, [42]), [null, 42], 'merges null into an array');
+
     t.deepEqual(utils.merge({ a: 'b' }, { a: 'c' }), { a: ['b', 'c'] }, 'merges two objects with the same key');
 
     var oneMerged = utils.merge({ foo: 'bar' }, { foo: { first: '123' } });