Documentation for Package: Handle unsaved files

Before this update the command would display an error if the current
TeX document was not already stored on disk.

Thanks to Tim Bates who reported this problem.

Support/lib/Python/tex.py

@@ -300,6 +300,8 @@ def find_tex_directives(texfile, ignore_root_loops=False):
         >>> chdir('../..')
 
     """
+    if not texfile:
+        return {}
     root_chain = [texfile]
     directive_regex = compile(r'%\s*!T[E|e]X\s+([\w-]+)\s*=\s*(.+)')
     directives = {}