Stuart McLean <makhector@gmail.com> writes:

> Now, _from the indirect buffer_ I want a sparse tree as follows `C-c
> /' (org-sparse-tree) and at the prompt I type `p', enter the property
> name "CATEGORY" with the value "work"
>
> The message in the echo area is Wrong type argument: stringp, nil

It's because the indirect buffer doesn't have a `buffer-file-name'.

This small patch against latest Org 5.13d should fix it: