opencv video_stream crash for webcam

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Hi, Im using ROS kinetic with ubuntu 16

I tried to run the following:

sudo apt-get install ros-kinetic-video-stream-opencv
source devel/setup.bash
roslaunch video_stream_opencv webcam.launch

it opens a small display window but its dark and than I get an error message which states: "sorry, the application video_stream has stopped unexpectedly."

on the command prompt there's the following output:

... logging to /home/tester/.ros/log/7c3f439c-215d-11e9-93d6-a434d94983a6/roslaunch-tester-XPS-13-9350-20451.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://tester-XPS-13-9350:44108/

SUMMARY


PARAMETERS
 * /rosdistro: kinetic
 * /rosversion: 1.12.12
 * /webcam/webcam_stream/buffer_queue_size: 1
 * /webcam/webcam_stream/camera_info_url: 
 * /webcam/webcam_stream/camera_name: webcam
 * /webcam/webcam_stream/flip_horizontal: False
 * /webcam/webcam_stream/flip_vertical: False
 * /webcam/webcam_stream/fps: 30.0
 * /webcam/webcam_stream/frame_id: webcam_optical_frame
 * /webcam/webcam_stream/height: 0
 * /webcam/webcam_stream/loop_videofile: False
 * /webcam/webcam_stream/set_camera_fps: 30.0
 * /webcam/webcam_stream/video_stream_provider: 0
 * /webcam/webcam_stream/width: 0

NODES
  /webcam/
    webcam_image_view (image_view/image_view)
    webcam_stream (video_stream_opencv/video_stream)

ROS_MASTER_URI=http://localhost:11311

process[webcam/webcam_stream-1]: started with pid [20468]
process[webcam/webcam_image_view-2]: started with pid [20469]
[ INFO] [1548701307.750201298]: Resource video_stream_provider: 0
[ INFO] [1548701307.750265122]: Getting video from provider: /dev/video0
[ INFO] [1548701307.969115605]: Video stream provider type detected: videodevice
[ INFO] [1548701307.972647577]: Camera name: webcam
[ INFO] [1548701307.975877216]: Setting camera FPS to: 30
[ INFO] [1548701307.979017728]: Camera reports FPS: 30
[ INFO] [1548701307.983787903]: Setting buffer size for capturing frames to: 1
[ INFO] [1548701307.988602391]: Throttling to fps: 30
[ INFO] [1548701307.991712224]: Publishing with frame_id: webcam_optical_frame
[ INFO] [1548701307.994771983]: Provided camera_info_url: ''
[ INFO] [1548701307.998538313]: Flip horizontal image is: false
[ INFO] [1548701308.002029133]: Flip vertical image is: false
[ INFO] [1548701308.015348365]: using default calibration URL
[ INFO] [1548701308.015553150]: camera calibration URL: file:///home/tester/.ros/camera_info/webcam.yaml
[ INFO] [1548701308.015712941]: Unable to open camera calibration file [/home/tester/.ros/camera_info/webcam.yaml]
[ WARN] [1548701308.015782408]: Camera calibration file /home/tester/.ros/camera_info/webcam.yaml not found.
[ INFO] [1548701308.015847803]: Opened the stream, starting to publish.
[ WARN] [1548701308.616463773]: No calibration file given, publishing a reasonable default camera info.
[ INFO] [1548701308.616540568]: The image width is: 640
[ INFO] [1548701308.616565884]: The image height is: 480
[webcam/webcam_stream-1] process has died [pid 20468, exit code -11, cmd /opt/ros/kinetic/lib/video_stream_opencv/video_stream camera:=image_raw __name:=webcam_stream __log:=/home/tester/.ros/log/7c3f439c-215d-11e9-93d6-a434d94983a6/webcam-webcam_stream-1.log].
log file: /home/tester/.ros/log/7c3f439c-215d-11e9-93d6-a434d94983a6/webcam-webcam_stream-1*.log

What am I doing wrong and how do I solve this?

thank you!