The MDL file shouldn't be required for the server to start

[goldmedal]

Description

The Wren engine provides the deploy API for MDL deployment after the server has started. The MDL file should not be required for the server to start.

Currently, if we attempt to start the server with a non-existent MDL file path, the server cannot be started. Furthermore, if we provide an empty file (non-JSON), the server can be started but the deploy API will throw an error at least twice.