--unknown option reports an error

[dbengsch]

When I use the --unknown option on my project, the following error is triggered :

npm-license --unknown

/usr/local/lib/node_modules/npm-license/lib/index.js:124
            if (options.unknown && data[item].licenses !== UNKNOWN && data[item].licenses.indexOf('*') === -1)
                                                                                         ^

TypeError: Cannot read property 'indexOf' of undefined
    at /usr/local/lib/node_modules/npm-license/lib/index.js:124:90
    at Array.forEach (native)
    at /usr/local/lib/node_modules/npm-license/lib/index.js:123:34
    at /usr/local/lib/node_modules/npm-license/node_modules/read-installed/read-installed.js:142:5
    at /usr/local/lib/node_modules/npm-license/node_modules/read-installed/read-installed.js:263:14
    at cb (/usr/local/lib/node_modules/npm-license/node_modules/slide/lib/async-map.js:47:24)
    at /usr/local/lib/node_modules/npm-license/node_modules/read-installed/read-installed.js:263:14
    at cb (/usr/local/lib/node_modules/npm-license/node_modules/slide/lib/async-map.js:47:24)
    at /usr/local/lib/node_modules/npm-license/node_modules/read-installed/read-installed.js:263:14
    at cb (/usr/local/lib/node_modules/npm-license/node_modules/slide/lib/async-map.js:47:24)

When I use npm-license | grep -i unknown , I don't have any output, so I would guess it only occurs when there is no unknown license.