How to fix typescript file missed by yo @microsoft/sharepoint setup command

when i first executed yo @microsoft/sharepoint to generate a web part, the return was corrected, However the style sheet typescript was missing after i ran the  yo @microsoft/sharepoint in the same project.

 the root cause of this issue is that i had load the lasted change from microsoft sharpeoint page framewrok with this command  run npm i -g @microsoft/generator-sharepoint@latest

it really messes up development enviroment, fortunately the microsoft offer the work around for this mess. the following steps is provided by microsoft.

"

1.  - Run npm update then npm prune then npm dedupe
   This will update all the packages then optimize the node_modules folder size.
2.  - Run gulp nuke to clean up any old build artifact
3. - Run gulp to build your updated project

"

you can find more information regarding the above steps from this link

https://github.com/SharePoint/sp-dev-docs/wiki/Release-Notes-Drop-4-and-MDL2


Update: in the lastest release, microsoft had remove the typescript object for the stylesheet. when you create the sharepoint web part from yo @microsoft/sharepoint with latest drop. you will not see any typescript object for stylesheet.