error while generating doc

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I have added my repository to doclets (https://github.com/mtrevisan/library), added the .doclets.yml accordingly (https://github.com/mtrevisan/library/blob/dev/.doclets.yml), and then it landed me to this page: https://doclets.io/mtrevisan/library/dev, giving me the following error:

`TypeError: /usr/src/app/views/doclayout.jade:19
17| ul.args
18| if func.params
19| each param in _.filter(func.params, function(param) {return param.name.indexOf('.') === -1;})
20| li(class=param.optional ? 'optional' : undefined)= param.name
21| if !isCtor && func.returns && func.returns[0] && func.returns[0].type
22| - var names = _.map(func.returns[0].type.names, tools.shortName);

Cannot read property 'indexOf' of undefined
at eval (eval at (/usr/src/app/node_modules/jade/lib/index.js:218:8), :1645:71)
at /usr/src/app/node_modules/underscore/underscore.js:227:11
at Function._.each._.forEach (/usr/src/app/node_modules/underscore/underscore.js:153:9)
at Function._.filter._.select (/usr/src/app/node_modules/underscore/underscore.js:226:7)
at Object.eval (eval at (/usr/src/app/node_modules/jade/lib/index.js:218:8), :1645:17)
at Object.jade_mixins.funcdeclx.jade_interp [as funcdeclx](eval at %28/usr/src/app/node_modules/jade/lib/index.js:218:8%29, :1677:4)
at Object.jade_mixins.title.jade_interp [as title](eval at %28/usr/src/app/node_modules/jade/lib/index.js:218:8%29, :3654:25)
at Object.jade_mixins.doclet.jade_interp [as doclet](eval at %28/usr/src/app/node_modules/jade/lib/index.js:218:8%29, :4468:21)
at eval (eval at (/usr/src/app/node_modules/jade/lib/index.js:218:8), :4574:22)
at eval (eval at (/usr/src/app/node_modules/jade/lib/index.js:218:8), :4599:4)
at eval (eval at (/usr/src/app/node_modules/jade/lib/index.js:218:8), :4760:22)
at res (/usr/src/app/node_modules/jade/lib/index.js:219:38)
at Object.exports.renderFile (/usr/src/app/node_modules/jade/lib/index.js:380:38)
at Object.exports.renderFile (/usr/src/app/node_modules/jade/lib/index.js:370:21)
at View.exports.__express [as engine](/usr/src/app/node_modules/jade/lib/index.js:417:11)
at View.render (/usr/src/app/node_modules/express/lib/view.js:126:8)`

Start with views/doclayout.jade at line 19 and reproduce the error using the linked mtrevisan/library repository and its .doclets.yml configuration. Inspect the generated parameter data behind the failing filter and verify that the documentation page renders without the TypeError.

Written by the indexing model from the issue text.