Revert getStaticData to only return Promise

packages/next/next-server/lib/router/router.ts

@@ -526,25 +526,18 @@ export default class Router implements BaseRouter {
  return routeInfo
  }
 
- // if we have data in cache resolve with the data
- // if not we we resolve with fallback routeInfo
-
+ // resolve with fallback routeInfo and promise for data
  if (isSSG || isSSP) {
- const dataRes = isSSG
- ? this._getStaticData(as)
- : this._getServerData(as)
-
- return Promise.resolve(
- typeof dataRes.then !== 'function'
- ? handleData(dataRes)
- : {
- ...routeInfo,
- props: {},
- dataRes: this._getData(() =>
- dataRes.then((props: any) => handleData(props))
- ),
- }
- )
+ return Promise.resolve({
+ ...routeInfo,
+ props: {},
+ dataRes: this._getData(() =>
+ (isSSG
+ ? this._getStaticData(as)
+ : this._getServerData(as)
+ ).then((props: any) => handleData(props))
+ ),
+ })
  }
 
  return this._getData<RouteInfo>(() =>
@@ -755,11 +748,11 @@ export default class Router implements BaseRouter {
  })
  }
 
- _getStaticData = (asPath: string): Promise<object> | any => {
+ _getStaticData = (asPath: string): Promise<object> => {
  const pathname = prepareRoute(parse(asPath).pathname!)
 
  return process.env.NODE_ENV === 'production' && this.sdc[pathname]
- ? this.sdc[pathname]
+ ? Promise.resolve(this.sdc[pathname])
  : fetchNextData(pathname, null, data => (this.sdc[pathname] = data))
  }