Fix bug when trying to use in on primitive

src/index.test.js

@@ -57,6 +57,17 @@ test('Matches always when pattern equals value', check(gen.any, (t, val) => {
   patroon(val, () => t.end())(val)
 }))
 
+test('Matches when empty array matches with empty array', t => {
+  patroon([], () => t.end())([])
+})
+
+test('May or may not match with any value', check(gen.any, gen.any, (t, a, b) => {
+  patroon(
+    a, () => t.end(),
+    _, () => t.end()
+  )(b)
+}))
+
 test('Matches none of the patterns and throws', t => {
   t.plan(1)
   t.throws(() =>

src/walkable.js

@@ -1,4 +1,4 @@
-const { isEmpty, isFunction, isNil } = require('./helpers')
+const { isEmpty, isFunction, isNil, isPrimitive } = require('./helpers')
 
 function walk (config, transform, item, path = []) {
   if (config.isLeafe(item)) { return transform(item, path) }
@@ -52,7 +52,7 @@ function path (pth, v, errorData) {
 
   const [key, ...rest] = pth
 
-  if (isNil(v) || !(key in v)) {
+  if (isPrimitive(v) || !(key in v)) {
     const error = new PathError(
       `Cannot read path ${pth}.`)