In Windows, opening a file without default program does nothing (in VSCode)

When trying to open a file that has no association with any program, nothing happens and no error is returned. Normally in Windows a selector is displayed that allows the user to choose which application to use, but this does not happen.

Start by locating the Windows-specific path-opening entry point and reproduce the behavior with a file that has no associated program. Trace how the system response is handled, then verify that Windows shows its application chooser or returns an error instead of silently doing nothing.

Written by the indexing model from the issue text.