JUCE Assertion failure in juce_AudioSampleBuffer.h:246

Thread 17 "helm" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff0e7d700 (LWP 8850)]
0x0000000000466a25 in SynthBase::processAudio (this=0x22a4be8, buffer=0x7ffff0e7cb50, channels=2, samples=256, offset=0)
    at ../../../src/common/synth_base.cpp:172
172	      channelData[i] = synth_output[i];
(gdb) bt
#0  0x0000000000466a25 in SynthBase::processAudio (this=0x22a4be8, buffer=0x7ffff0e7cb50, channels=2, samples=256, offset=0)
    at ../../../src/common/synth_base.cpp:172
#1  0x000000000050b556 in HelmStandaloneEditor::getNextAudioBlock (this=0x22a3a30, buffer=...)
    at ../../../src/standalone/helm_standalone_editor.cpp:101
#2  0x000000000056a760 in juce::AudioSourcePlayer::audioDeviceIOCallback (this=0x22a3e50, inputChannelData=0x2cd5060,
    totalNumInputChannels=0, outputChannelData=0x2aa6160, totalNumOutputChannels=1, numSamples=1024)
    at ../../../JUCE/modules/juce_audio_devices/sources/juce_AudioSourcePlayer.cpp:142
#3  0x0000000000567c83 in juce::AudioDeviceManager::audioDeviceIOCallbackInt (this=0x22a3b08, inputChannelData=0x2cd5060,
    numInputChannels=0, outputChannelData=0x2aa6160, numOutputChannels=1, numSamples=1024)
    at ../../../JUCE/modules/juce_audio_devices/audio_io/juce_AudioDeviceManager.cpp:797
#4  0x00000000005752a7 in juce::AudioDeviceManager::CallbackHandler::audioDeviceIOCallback (this=0x22a15d0, ins=0x2cd5060, numIns=0,
    outs=0x2aa6160, numOuts=1, numSamples=1024) at ../../../JUCE/modules/juce_audio_devices/audio_io/juce_AudioDeviceManager.cpp:56
#5  0x000000000057767a in juce::JackAudioIODevice::process (this=0x264fce0, numSamples=1024)
    at ../../../JUCE/modules/juce_audio_devices/native/juce_linux_JackAudio.cpp:392
#6  0x0000000000577719 in juce::JackAudioIODevice::processCallback (nframes=1024, callbackArgument=0x264fce0)
    at ../../../JUCE/modules/juce_audio_devices/native/juce_linux_JackAudio.cpp:404
#7  0x00007ffff0e9130e in ?? () from /usr/lib/libjack.so.0
#8  0x00007ffff0e90ad8 in ?? () from /usr/lib/libjack.so.0
#9  0x00007ffff0ea8330 in ?? () from /usr/lib/libjack.so.0
#10 0x00007ffff6c9d454 in start_thread () from /usr/lib/libpthread.so.0
#11 0x00007ffff5f357df in clone () from /usr/lib/libc.so.6