fix: remove config.build.ssr assert (#3096)

Author: brillout

packages/vike/src/node/vite/plugins/pluginCommon.ts

@@ -99,8 +99,6 @@ function pluginCommon(vikeVitePluginOptions: unknown): Plugin[] {
       config: {
         order: 'post',
         async handler(configFromUser) {
-          assertViteBuildSsr(configFromUser)
-
           let configFromVike: UserConfig = { server: {}, preview: {} }
           const vikeConfig = await getVikeConfigInternal()
 
@@ -199,8 +197,3 @@ async function emitServerEntryOnlyIfNeeded(config: ResolvedConfig) {
     config.vitePluginServerEntry.disableServerEntryEmit = true
   }
 }
-
-function assertViteBuildSsr(configFromUser: UserConfig) {
-  // https://github.com/vikejs/vike/issues/3010
-  assertUsage(configFromUser.build?.ssr === undefined, "Don't set vite.build.ssr")
-}