User Script causes Image panel to stop updating

[jtbandes]

Description When a user script is added, the image panel does not update as expected.

• Version: latest web
• OS: Chrome / macos

Steps To Reproduce

• Create a layout with one Image panel
• Load https://librealsense.intel.com/rs-tests/TestData/stairs.bag
• Select the /device_0/sensor_1/Color_0/image/data topic
• Play the bag and observe that images appear and continue to update through the end of the bag.
• Add a User Scripts panel and copy/paste the user script from #4080.
• Load the bag again and play. Observe that a black frame appears, but then subsequent frames do not appear.

https://user-images.githubusercontent.com/14237/183790033-1c0732af-ce38-40c1-a71e-e7c2cb7d24ef.mov