fix(function): remove extra space for non-existing functions

Author: akinomyoga

completions/function

@@ -8,7 +8,8 @@ _function()
     if ((cword == 1)); then
         COMPREPLY=($(compgen -A function -- "$cur"))
     else
-        COMPREPLY=("() $(type -- "${words[1]}" 2>/dev/null | command sed -e 1,2d)")
+        local funcdef=$(type -- "${words[1]}" 2>/dev/null | command sed -e 1,2d)
+        COMPREPLY=("()${funcdef:+ $funcdef}")
     fi
 } &&
     complete -F _function function