fix(): '/:id' is not supposed to be matched by route

* test(): test bug where a :key param is appended to an existing route

* fix(): fix bug where '/:id' is not supposed to be matched by route

When navigating to `/` when `/` and `/:id` is defined it still tries to match
`/:id` while id will be undefined, causing null to be the route matched.

src/index.js

@@ -82,7 +82,7 @@ function switchPath(sourcePath, routes) {
       matchedValue = routes[pattern]
     }
 
-    const params = matchesWithParams(sourcePath, pattern)
+    const params = matchesWithParams(sourcePath, pattern).filter(Boolean)
 
     if (params.length > 0 && betterMatch(sourcePath, matchedPath)) {
       matchedPath = extractPartial(sourcePath, pattern)

test/index.js

@@ -213,4 +213,14 @@ describe('switchPath corner cases', () => {
     expect(path).to.be.equal('/home/123/456')
     expect(value).to.be.equal('123:456')
   })
+
+  it('should not match a :key type route if no params are given', () => {
+    const {path, value} = switchPath('/', {
+      '/': 'root',
+      '/:id': (id) => `$id`
+    })
+
+    expect(path).to.be.equal('/')
+    expect(value).to.be.equal('root')
+  })
 });