Uncaught TypeError: can't access property "slice", s is undefined

[hexagon6]

In mashlib, using the deployed databrowser: https://solidos.github.io/mashlib/dist/browse.html for my own solid pod, the TypeError message mentioned in the title occurs.

When I try to add a new item by clicking on the + sign in my pod, nothing happens in the UI

and in the dev console I can see this error trace:

Uncaught TypeError: can't access property "slice", s is undefined
    outlinePredicateTD manager.js:206
    generateRequest userInput.js:1293
    addNewPredicateObject userInput.js:99
    render defaultPane.js:62
    render defaultPane.js:61
    propertyTable manager.js:680
    promise callback*7981/t.default/this.propertyTable manager.js:674
    u manager.js:1649
    z manager.js:1743
    nowOrWhenFetched fetcher.js:890
    promise callback*nowOrWhenFetched fetcher.js:886
    z manager.js:1740
    GotoSubject manager.js:1869
    render folderPane.js:81
    promise callback*render folderPane.js:77
    propertyTable manager.js:680
    promise callback*7981/t.default/this.propertyTable manager.js:674
    u manager.js:1649
    z manager.js:1743
    nowOrWhenFetched fetcher.js:890
    promise callback*nowOrWhenFetched fetcher.js:886
    z manager.js:1740
    GotoSubject manager.js:1869
    go browse.html:28

related line 206: https://github.com/SolidOS/solid-panes/blob/6468b81e8ba1588a0694341bb5feb9336116994b/src/outline/manager.js#L248C5-L248C8

I assume the switch case of case 'BlankNode' does not assign the lab variable, therefore the .slice does not exist on undefined.