Due to this commit that landed in node 10.x: nodejs/node@0a0fbd5

The fs.close operation here: https://github.com/digitalbazaar/bedrock/blob/master/lib/loggers.js#L219

is calling it's callback with (err, undefined) instead of just (err) which results in async.waterfall passing undefined as the argument to the subsequent operation which in this case is expecting only callback where callback === undefined which leads to callback is not a function

I am working on a patch for node which may just be to revert to the previous behavior in node 8.x here: https://github.com/nodejs/node/blob/v8.x/lib/fs.js#L134-L136