you raise an interesting issue. It really is not a good idea to close your laptop lid with open files that you are developing and are presumably open with a [Full Access] account. I'm afraid I couldn't tell you which is worse!
The cheapest way I have found for running a test server is using Mac Mini (lower spec will do) with the Developer Subscription Server License. That way the server keeps running even if you close the laptop lid.
However this doesn't answer the bigger question: is it safe to develop a file hosted on a server or should development ideally be done on the local machine?
Filemaker has a consistency checker: The FileMaker Pro Consistency Check | FileMaker
which can be run on a local file, and on the server. The server can verify your files when running a backup and email you if there is a problem, so you should be able to test this and let is all know!