I am seeing this when NR is starting.

[Just-another-pleb]

I have version 0.4.8

But I am not sure it is important.

TypeError: Cannot read property 'config' of null
    at addWidget (/home/me/.node-red/node_modules/node-red-dashboard/index.js:73:39)
    at Object.addWidget (/home/me/.node-red/node_modules/node-red-dashboard/index.js:137:48)
    at new LEDNodeConstructor (/home/me/.node-red/node_modules/node-red-contrib-ui-led/dist/nodes/ui_led/ui_led.js:30:29)
    at Object.createNode (/usr/lib/node_modules/node-red/node_modules/@node-red/runtime/lib/flows/util.js:493:31)
    at Flow.start (/usr/lib/node_modules/node-red/node_modules/@node-red/runtime/lib/flows/Flow.js:194:48)
    at start (/usr/lib/node_modules/node-red/node_modules/@node-red/runtime/lib/flows/index.js:345:33)
    at /usr/lib/node_modules/node-red/node_modules/@node-red/runtime/lib/flows/index.js:210:21
    at processTicksAndRejections (internal/process/task_queues.js:97:5)

Sorry if it has been fixed with 0.4.9

Thanks in advance.

Just updated the dashboard and your node to the latest.
Still happening.