fix: handle null in obj, handle empty string in path

Closes #35
Closes #36

src/index.js

@@ -4,6 +4,6 @@ export function dset(obj, keys, val) {
 	while (i < l) {
 		k = keys[i++];
 		if (k === '__proto__' || k === 'constructor' || k === 'prototype') break;
-		t = t[k] = (i === l) ? val : (typeof(x=t[k])===typeof(keys)) ? x : (keys[i]*0 !== 0 || !!~(''+keys[i]).indexOf('.')) ? {} : [];
+		t = t[k] = (i === l) ? val : ((x=t[k]) && typeof(x)===typeof(keys)) ? x : (k='+'+keys[i])*0 !== 0 || /\./.test(k) ? {} : []
 	}
 }

src/merge.js

@@ -20,6 +20,6 @@ export function dset(obj, keys, val) {
 	while (i < l) {
 		k = keys[i++];
 		if (k === '__proto__' || k === 'constructor' || k === 'prototype') break;
-		t = t[k] = (i === l) ? merge(t[k],val) : (typeof(x=t[k])===typeof keys) ? x : (keys[i]*0 !== 0 || !!~(''+keys[i]).indexOf('.')) ? {} : [];
+    t = t[k] = (i === l) ? merge(t[k],val) : ((x = t[k]) && typeof x === typeof keys) ? x : (k = '+' + keys[i]) * 0 !== 0 || /\./.test(k) ? {} : [];
 	}
 }

test/suites/objects.js

@@ -91,5 +91,25 @@ export default function (dset, isMerge) {
 		}
 	});
 
+  objects(`should ${verb} empty string property`, () => {
+    let { input } = prepare({});
+
+    dset(input, ['hello', ''], 123);
+
+    assert.equal(input, {
+      hello: { '': 123 },
+    });
+  });
+
+  objects(`should ${verb} null values`, () => {
+    let { input } = prepare({ hello: null });
+
+    dset(input, ['hello', 'a'], 123);
+
+    assert.equal(input, {
+      hello: { a: 123 },
+    });
+  });
+
 	objects.run();
 }