Second app - error Schema validation failed Data path ".assets[0]" should be object.

Versions

Angular CLI: 6.0.3
Node: 10.1.0
OS: win32 x64
Angular: 6.0.2
... animations, common, compiler, compiler-cli, core, forms
... http, language-service, platform-browser
... platform-browser-dynamic, router

Package                            Version
------------------------------------------------------------
@angular-devkit/architect          0.5.8
@angular-devkit/build-angular      0.5.8
@angular-devkit/build-ng-packagr   0.6.0
@angular-devkit/build-optimizer    0.5.8
@angular-devkit/core               0.5.8
@angular-devkit/schematics         0.6.3
@angular/cli                       6.0.3
@ngtools/json-schema               1.1.0
@ngtools/webpack                   6.0.0-rc.6
@schematics/angular                0.6.3
@schematics/update                 0.6.3
ng-packagr                         3.0.0-rc.3
rxjs                               6.1.0
typescript                         2.7.2
webpack                            4.6.0

Repro steps

I add second app to my existing app with ng g application office --routing

Desired behavior

ng serve office - serving my second app

Observed behavior