form pane throws error e.indexOf is not a function

[josephguillaume]

The form pane fails render for, e.g. #Object

@prefix ui: <http://www.w3.org/ns/ui#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .

<#Object> a <#Class>.

<#Class> ui:annotationForm <#MyForm2> .

<#MyForm2>
    a ui:SingleLineTextField ; 
      ui:label "name" ;
      ui:property foaf:name

Error is:

Uncaught (in promise) TypeError: e.indexOf is not a function
    at o (uri.js:35)
    at Object.t.document (uri.js:50)
    at pane.js:76
    at fetcher.js:1017

This occurs because a NamedNode is passed where a string is expected:
https://github.com/solid/solid-panes/blob/6ca75b8fdeb4f70744b59e574d7afe401554dd8b/src/form/pane.js#L93
https://github.com/linkeddata/rdflib.js/blob/1a90b03cef433f456d518e16440fb0281368c445/src/uri.ts#L33
https://github.com/linkeddata/rdflib.js/blob/1a90b03cef433f456d518e16440fb0281368c445/src/uri.ts#L19