Add failsafe to OSC save patch to user patch dir

[gitsmol]

Trying again after some clang formatting fails...

[baconpaul]

There are cases where this operation can throw an fs::filesystem_error which uncaught here would crash your OSC instance.

You probably want

try {
   /// your code here
} catch (const fs::filesystem_error &e)
{
  // report e.what()
}

to be safe