trying to navigate when blocks are null causes crash

[andrewrk]

timers.js:103
if (!process.listeners('uncaughtException').length) throw e;
^
TypeError: Cannot read property 'boundingBox' of null
at isSafe (/home/andy/dev/mc-bot-server/node_modules/rbot/node_modules/mineflayer-navigate/index.js:345:17)
at Object.getNeighbors as neighbor
at aStar (/home/andy/dev/mc-bot-server/node_modules/rbot/node_modules/mineflayer-navigate/node_modules/a-star/index.js:50:28)
at findPathSync (/home/andy/dev/mc-bot-server/node_modules/rbot/node_modules/mineflayer-navigate/index.js:74:19)
at EventEmitter.navigateTo as to
at moveTo (/home/andy/dev/mc-bot-server/node_modules/rbot/task.js:114:16)
at /home/andy/dev/mc-bot-server/node_modules/rbot/achieve.js:70:18
at listAux (/home/andy/dev/mc-bot-server/node_modules/rbot/achieve.js:119:7)
at achieveList (/home/andy/dev/mc-bot-server/node_modules/rbot/achieve.js:124:2)
at achieve (/home/andy/dev/mc-bot-server/node_modules/rbot/achieve.js:111:2)
at listAux (/home/andy/dev/mc-bot-server/node_modules/rbot/achieve.js:116:28)

[fatlotus]

I'm not sure how to fix this, and am still getting it in the latest version of Navigate. Thoughts?

[nevercast]

Old issue clearly, but a fix would be to regard null blocks as air.