Here is the minified code snippet

if (r.rootNode.children && this.treeClear(t),
    s = s || this.options.source)
        "string" == typeof s && e.error("Not implemented");

Please let me know if it is the correctly unminified by me?

if(r.rootNode.children)
    this.treeClear(t);
    
s = s || this.options.source

if(s)
    if("string" == typeof s)
        e.error("Not implemented");