Does not validate memory size

[carmine]

I'm trying to launch an instance with the memory specified. When forgetting to specify the quantity of memory, you get the error above. It'd be good to provide a check and print a message.

Here's an example:

| => multipass launch bionic -n fred -c 4 -m 1
Starting openkilda \[2019-02-04T00:42:27.811] [error] [fred] mptable requires mapped mem

Of course, the issue is that I specified 1 byte for memory :-) .. so maybe check that at least X bytes is specified?

[carmine]

Also, whereas you can delete the VM, when you try to purge, I get this message

 => multipass purge
purge failed: cannot connect to the multipass socket
Please ensure multipassd is running and '/var/run/multipass_socket' is accessible

This seems to only happen when using a dodgy -m size.

[Saviq]

That second one is multipassd crashing when purging a broken instance: #585 - agreed we should validate the memory input :)

[ricab]

This wasn't automatically closed for some reason. Closing manually.