Cannot convert undefined or null to object

[Ostaer]

I get an error
apidoc-markdown -p . -o text.rd
undefined:25
throw err;
^

TypeError: ejs:30
28| <%-: data[group][sub][0].type | upcase %> <%= data[group][sub][0].url %>
29| ```

30|
31| <% if (data[group][sub][0].header && data[group][sub][0].header.fields.Header.length) { -%>
32| ### Headers
33|
xdl
Cannot convert undefined or null to object
at Function.keys ()
at eval (eval at exports.compile (C:\Users\name\AppData\Roaming\npm\node_modules\apidoc-markdown\node_modules\ejs\lib\ejs.js:237:14), :32:114)
at Array.forEach ()
at eval (eval at exports.compile (C:\Users\name\AppData\Roaming\npm\node_modules\apidoc-markdown\node_modules\ejs\lib\ejs.js:237:14), :30:1192)
at Array.forEach ()
at eval (eval at exports.compile (C:\Users\name\AppData\Roaming\npm\node_modules\apidoc-markdown\node_modules\ejs\lib\ejs.js:237:14), :30:964)
at eval (eval at exports.compile (C:\Users\name\AppData\Roaming\npm\node_modules\apidoc-markdown\node_modules\ejs\lib\ejs.js:237:14), :46:21)
at C:\Users\name\AppData\Roaming\npm\node_modules\apidoc-markdown\node_modules\ejs\lib\ejs.js:250:15
at Object. (C:\Users\name\AppData\Roaming\npm\node_modules\apidoc-markdown\index.js:88:31)
at Module._compile (module.js:643:30)