fix(errors): throws with invalid route objects

Closes #1892
Throws for missing component, components or redirect and also when components is empty

Author: posva

Diff for: src/create-route-map.js

@@ -52,6 +52,10 @@ function addRouteRecord (
   const { path, name } = route
   if (process.env.NODE_ENV !== 'production') {
     assert(path != null, `"path" is required in a route configuration.`)
+    assert(route.component != null || route.redirect != null || route.components != null, `One of the following options "component", "components" or "redirect" is required for route "${path}"`)
+    if (route.components) {
+      assert(route.components.length, `"components" array cannot be empty for route "${path}"`)
+    }
     assert(
       typeof route.component !== 'string',
       `route config "component" for path: ${String(path || name)} cannot be a ` +

Diff for: test/unit/specs/create-map.spec.js

@@ -71,6 +71,48 @@ describe('Creating Route Map', function () {
     expect(console.warn.calls.argsFor(0)[0]).toMatch('vue-router] Named Route \'bar\'')
   })
 
+  it('in development, throws if path is missing', function () {
+    process.env.NODE_ENV = 'development'
+    expect(() => {
+      maps = createRouteMap([{ component: Bar }])
+    }).toThrowError(/"path" is required/)
+  })
+
+  it('in development, throws if component, components or redirect is missing', function () {
+    process.env.NODE_ENV = 'development'
+    expect(() => {
+      maps = createRouteMap([{ path: '/' }])
+    }).toThrowError(/"component", "components" or "redirect" is required/)
+  })
+
+  it('in development, does not throw if component is provided', function () {
+    process.env.NODE_ENV = 'development'
+    expect(() => {
+      maps = createRouteMap([{ path: '/', component: Bar }])
+    }).not.toThrow()
+  })
+
+  it('in development, does not throw if components is provided', function () {
+    process.env.NODE_ENV = 'development'
+    expect(() => {
+      maps = createRouteMap([{ path: '/', components: [{ component: Bar, path: '' }] }])
+    }).not.toThrow()
+  })
+
+  it('in development, does not throw if redirect is provided', function () {
+    process.env.NODE_ENV = 'development'
+    expect(() => {
+      maps = createRouteMap([{ path: '/', redirect: '/home' }])
+    }).not.toThrow()
+  })
+
+  it('in development, throws if components is empty', function () {
+    process.env.NODE_ENV = 'development'
+    expect(() => {
+      maps = createRouteMap([{ path: '/', components: [] }])
+    }).toThrowError(/"components" array cannot be empty/)
+  })
+
   it('in production, it has not logged this warning', function () {
     maps = createRouteMap(routes)
     expect(console.warn).not.toHaveBeenCalled()