fix: special case merging when merging keys of length zero

src/merge.js

@@ -17,6 +17,11 @@ export function merge(a, b, k) {
 export function dset(obj, keys, val) {
 	keys.split && (keys=keys.split('.'));
 	var i=0, l=keys.length, t=obj, x, k;
+	if (l === 0) {
+		merge(t, val)
+		return
+	}
+
 	while (i < l) {
 		k = keys[i++];
 		if (k === '__proto__' || k === 'constructor' || k === 'prototype') break;

test/merge.js

@@ -177,6 +177,23 @@ dsets('should merge array at path notation', () => {
 	]);
 });
 
+dsets('should be able to insert at root', () => {
+	let input = {};
+	dset(input, [], { hero: { id: "A" }});
+	assert.equal(input, {
+		hero: {
+			id: "A"
+		}
+	});
+});
+
+dsets('should ignore root merge of value without key', () => {
+	let input = {};
+	dset(input, [], "A");
+	assert.instance(input, Object);
+	assert.equal(input, {});
+});
+
 dsets.run();
 
 // ---