Describe and Describe extend command full functionality?

[hacker0limbo]

So i checked the source code and find such lines in the KSQLMain.ts file:

    vscode.commands.registerCommand('ksql.explorer.describe_extended', (node) => {
        return vscode.commands.executeCommand('vscode.previewHtml', vscode.Uri.parse("ksql:"+node.label+"?extended=true")).then((success) => {
        }, (reason) => {
            vscode.window.showErrorMessage(reason);
        });
    });

Looks like it is registering a command Describe and Describe Extend, and trying execute previewHTML command when those two command are activated.

However when i trying to execute those two commands in the vscode command palette, it prompts error message like this( I added some logs in order to show the complete error message):

I am new to developing vscode extension, and just wondering what is the real functionalities of those two commands and what will be the final look like of it?

Cheers!