Initialise a new BoxApplet<Msg, Params> instance.
Will error if called in a client applet.
The generic Msg should be set to the type of the applet-messages to send and receive between.
The optional generic Params should be set to the type of the custom parameters that were passed to the applet on start. (from the startApplet message).
Initialise a new BoxApplet
<Msg, Params>instance. Will error if called in a client applet.Msgshould be set to the type of the applet-messages to send and receive between.Paramsshould be set to the type of the custom parameters that were passed to the applet on start. (from the startApplet message).