Notice: Notice: Undefined variable: root_term_index in _taxonomy_manager_tree_get_first_path() (line 483 of taxonomy_manager.module)

I receive this notice:
"Notice: Notice: Undefined variable: root_term_index in _taxonomy_manager_tree_get_first_path() (line 483 of path/to/taxonomy_manager.module)" when access a categories through taxonomy_manager UI.
I make a patch & fix this error sucessfully.
But another warning appear after apply patch is:
"Warning: Cannot access property on non-object in taxonomy_manager_get_partial_tree() (line 550 of path/to/taxonomy_manager.module"
And I don't know how to fix above warning. Please help.