ng generate module produce wrong code for specific code pattern

# 🐞 Bug report

### Command (mark with an `x`)

```
- [ ] new
- [ ] build
- [ ] serve
- [ ] test
- [ ] e2e
- [x] generate
- [ ] add
- [ ] update
- [ ] lint
- [ ] xi18n
- [ ] run
- [ ] config
- [ ] help
- [ ] version
- [ ] doc
```

### Is this a regression?

No.

### Description

The `ng generate module` produce wrong code.

## 🔬 Minimal Reproduction

```sh
ng new demo1 --routing --style css
cd demo1
ng g c test1
```

Add route config in `src/app/app-routing.module.ts` just like below:

```ts
const route1 = { path: 'test1', component: Test1Component };
const routes: Routes = [
route1
];
```

Then I creating an lazy-loaded module named `test`.

```sh
ng g module test --route test --module app
```

Then the route config will turn into this. And this is wrong.

```ts
const route1 = { path: 'test1', component: Test1Component };
const routes: Routes = [,
{ path: 'test', loadChildren: () => import('./test/test.module').then(m => m.TestModule) }
route1
];
```

## 🔥 Exception or Error

ERROR in Cannot read property 'loadChildren' of undefined

## 🌍 Your Environment

Angular CLI: 8.3.13

Node: 10.16.3

OS: win32 x64

Angular: 8.2.11

... animations, common, compiler, compiler-cli, core, forms

... language-service, platform-browser, platform-browser-dynamic

... router


Package                           Version

-----------------------------------------------------------

@angular-devkit/architect         0.803.13

@angular-devkit/build-angular     0.803.13

@angular-devkit/build-optimizer   0.803.13

@angular-devkit/build-webpack     0.803.13

@angular-devkit/core              8.3.13

@angular-devkit/schematics        8.3.13

@angular/cli                      8.3.13

@ngtools/webpack                  8.3.13

@schematics/angular               8.3.13

@schematics/update                0.803.13

rxjs                              6.4.0

typescript                        3.5.3

webpack                           4.39.2

**Anything else relevant?**

Reproduce the issue with the listed ng new, ng g c, and ng g module commands, then inspect src/app/app-routing.module.ts before and after generation. Done means the lazy-loaded route is inserted without invalid commas or dropped separators, while the existing route1 remains valid.

Written by the indexing model from the issue text.