fix: fnameescape in from_entry (#454)

if entry.path is nil vim.fn.fnameescape will return null which results
in all other option no longer be checked

lua/telescope/from_entry.lua

@@ -11,7 +11,7 @@ This will provide standard mechanism for accessing information from an entry.
 local from_entry = {}
 
 function from_entry.path(entry, validate)
-  local path = vim.fn.fnameescape(entry.path)
+  local path = entry.path and vim.fn.fnameescape(entry.path) or nil
   if path == nil then path = entry.filename end
   if path == nil then path = entry.value end
   if path == nil then print("Invalid entry", vim.inspect(entry)); return end