Just noticed this as I am repeatedly stopping/starting NR.
TypeError: Cannot read property 'config' of null
at addWidget (/home/pi/.node-red/node_modules/node-red-dashboard/index.js:73:39)
at Object.addWidget (/home/pi/.node-red/node_modules/node-red-dashboard/index.js:137:48)
at new LEDNodeConstructor (/home/pi/.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:87:27)
at Flow.start (/usr/lib/node_modules/node-red/node_modules/@node-red/runtime/lib/flows/Flow.js:206:48)
at start (/usr/lib/node_modules/node-red/node_modules/@node-red/runtime/lib/flows/index.js:371:33)
LED node...
Just sharing.