AssertionError: false == true at Board._handleAcknowledge

[poeml]

I frequently get this error message when homeduino tries to send data.

error [pimatic]: A uncaught exception occured: AssertionError: false == true
    at Board._handleAcknowledge (/home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/lib/board.js:315:5)
    at Board._onLine (/home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/lib/board.js:140:21)
    at SerialPortDriver.<anonymous> (/home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/lib/board.js:83:22)
    at emitOne (events.js:77:13)
    at SerialPortDriver.emit (events.js:169:7)
    at SerialPort.<anonymous> (/home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/lib/driver/serialport.js:64:24)
    at emitOne (events.js:77:13)
    at SerialPort.emit (events.js:169:7)
    at /home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/node_modules/serialport/parsers.js:25:17
    at Array.forEach (native)
    at Object.parser (/home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/node_modules/serialport/parsers.js:24:13)
    at Object.SerialPort.opts.dataCallback (/home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/node_modules/serialport/serialport.js:181:12)
    at SerialPortFactory.SerialPort._emitData (/home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/node_modules/serialport/serialport.js:396:20)
    at afterRead (/home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/node_modules/serialport/serialport.js:372:20)
    at /home/pi/pimatic-app/node_modules/pimatic-homeduino/node_modules/homeduino/node_modules/serialport/serialport.js:388:9
    at FSReqWrap.wrapper [as oncomplete] (fs.js:576:17)
 This is most probably a bug in pimatic or in a module, please report it!

This occured already with 0.8, and continues to occur with 0.9.

Otherwise, homeduino works (via an Arduino Nano connected via USB) most of the time, but I often have issues with sending - sometimes it times out. Pimatic then reports "Oops, timeout" via the browser, without logging anything in the log file (despite debug logging). It's quite unreliable and I don't know why. The above stack trace could probably one part of the problem, possibly the communication doesn't work reliably, but I already lowered the baud rate significantly and have no further idea...