'Could not find file ... bin\roslyn\csc.exe'

In Visual Studio 2017, when hitting + to run my ASP.NET Framework Web API server, I get:

Could not find file ... bin\roslyn\csc.exe:

Running Update-Package Microsoft.CodeDom.Providers.DotNetCompilerPlatform -r in the package manager console is not a permanent fix in the sense that the server error appears again when the package files are missing. How can I get rid of this error once and for all so that the needed packages are automatically (and silently) reinstalled as soon as I reopen, build, and run my Visual Studio solution?

Code to reproduce the error: https://user.it.uu.se/~hesc0353/RoslynError-reproduce.zip (Originally from https://github.com/aspnet/AspNetDocs/tree/master/aspnet/web-api/overview/advanced/calling-a-web-api-from-a-net-client/sample/server/ProductsApp)