Nan::ObjectWrap::Unref(): Assertion `!persistent().IsWeak()' failed.

[tbranyen]

This error happens when I call the list() function on a 1s interval poll. I do this to ensure that the camera is still connected and detect if new cameras have been added. Doing this causes a crash consistently:

18:38:56 0|index  | node /home/tim/git/remote-camera-control/server/index.js: ../../nan/nan_object_wrap.h:109: virtual void Nan::ObjectWrap::Unref(): Assertion `!persistent().IsWeak()' failed.

Commenting out the following line prevents the fatal exception from being raised. I suspect this indicates a race condition around dereferencing. Will dig and see if there is a way to safely guard around this as it's pretty annoying to have the Node process hard crash.

[tbranyen]

Some logs right before the crash:

19:07:09 0|index  | gp_port_info_list_get_info Getting info of entry 38 (45 available)...
19:07:09 0|index  | gp_port_set_timeout Setting port timeout to 5000 milliseconds.
19:07:09 0|index  | gp_port_set_settings Setting settings...
19:07:09 0|index  | gp_libusb1_update (old int=0, conf=-1, alt=-1) port usb:001,003, (new int=0, conf=-1, alt=-1) port usb:001,003
19:07:09 0|index  | gp_libusb1_update lowlevel libusb1 port not yet opened, no need for libusb changes
19:07:09 0|index  | gp_abilities_list_detect_usb Auto-detecting USB cameras...
19:07:09 0|index  | gp_libusb1_find_device_by_class_lib Looking for USB device (class 0x29a, subclass, 0xffffffff, protocol 0xffffffff)...
19:07:09 0|index  | gp_libusb1_find_device_by_class_lib Looking for USB device (class 0x6, subclass, 0x1, protocol 0x1)...
19:07:09 0|index  | gp_port_info_list_get_info Getting info of entry 39 (45 available)...
19:07:09 0|index  | gp_port_set_timeout Setting port timeout to 5000 milliseconds.
19:07:09 0|index  | gp_port_set_settings Setting settings...
19:07:09 0|index  | gp_libusb1_update (old int=0, conf=-1, alt=-1) port usb:003,002, (new int=0, conf=-1, alt=-1) port usb:003,002
19:07:09 0|index  | gp_libusb1_update lowlevel libusb1 port not yet opened, no need for libusb changes
19:07:09 0|index  | gp_abilities_list_detect_usb Auto-detecting USB cameras...
19:07:09 0|index  | gp_libusb1_find_device_lib Looking for USB device (vendor 0x4a9, product 0x319b)... found.
19:07:09 0|index  | gp_libusb1_find_device_lib Detected defaults: config 1, interface 0, altsetting 0, inep 81, outep 02, intep 83, class 06, subclass 01
19:07:09 0|index  | gp_abilities_list_detect_usb Found 'Canon EOS 50D' (0x4a9,0x319b)
19:07:09 0|index  | gp_port_free Freeing port...
19:07:09 0|index  | gp_port_close Closing port...
19:07:10 0|index  | node /home/tim/git/remote-camera-control/server/index.js: ../node_modules/nan/nan_object_wrap.h:109: virtual void Nan::ObjectWrap::Unref(): Assertion `!persistent().IsWeak()' failed.

[icheered]

I'm running into the same issue, did you ever solve it?

[tbranyen]

I worked around it using a function to "recover" after a crash.

https://github.com/tbranyen/remote-camera-control/blob/master/index.js#L12-L28

Looks like no substantial commits have landed since I opened this issue years ago, so this might be your best bet for now if you want to use this module.