debug: avoid abort that was causing Neovim quit to hang

Do not attempt to delete a command based on the first line of output
from ":command GoDebug" trying to stop debugging. The error was causing
the function to be aborted, which was in turn causing Neovim to hang
when trying to quit.

Author: bhcleek

autoload/go/debug.vim

@@ -320,6 +320,9 @@ endfunction
 function! go#debug#Stop() abort
   " Remove all commands and add back the default commands.
   for k in map(split(execute('command GoDebug'), "\n")[1:], 'matchstr(v:val, "^\\s*\\zs\\S\\+")')
+    if k is 'Name'
+      continue
+    endif
     exe 'delcommand' k
   endfor
   command! -nargs=* -complete=customlist,go#package#Complete GoDebugStart call go#debug#Start('debug', <f-args>)