Fornax generates a ghost file

[oluwandabira]

Describe the bug
Fornax is generating output for a generator with no generate function.

To Reproduce
Steps to reproduce the behaviour:

1. fornax new
2. Delete everything in contact.fsx
3. fornax build
4. See contact.html generated with content in it.

Expected behaviour
An error occurs, like say "Fornax couldn't detect a generator in this file" or something to that effect.

Environment (please complete the following information):

• OS: Windows 10 / Ubuntu 20.4
• Ionide version: 5.5.5
• VSCode version: 1.56.1
• dotnet SDK version: 5.0.203