[haji-ali]

I have four fixes that I hope are OK to submit as one PR. I recommend not squashing them, as they address separate issues.

The motivations are:

• Currently, if a file is deleted while its buffer is open, there is a chance that a directory will be created for the buffer. For me, this manifested as repeatedly deleting the directory containing an open buffer's file, only for Radian to recreate it.
• Using when-let (unstarred) produces a compilation warning.
• custom-file is currently loaded before any Radian variables are defined. This is the only file that is not compiled as part of Radian, so I wanted to use it to check whether Radian needs to be recompiled (for custom-related reasons). However, the Radian variables are not defined when it is loaded. Is there a reason why custom is loaded so early in Radian's initialisation cycle?
• kill-process is asynchronous. I believe we want delete-process here to ensure that we can start a new process with the same name.

[raxod502]

That all looks good to me! Thanks!