Problem getting PublishingWeb with JSOM

Hello everyone,

For my customer I need to implement a one click solution to build a SharePoint sub web and setup the security around it.

I decided not to use a SharePoint hosted app since it requires Site collection full control which I don't want to give to the user running this solution

I decided not to use a SharePoint provider app because of the infrastructural complexity behind that my client does not want to implement.

So I decided to go for a JSOM solution that is called through a Content Editor WebPart dropped on a page that renders the form and allows site creation with Web Full Control only instead of Site collection Full Control. (this is acceptable)

I managed to create the sub web, enable the publishing feature and create all the groups required by my solution, but I need to create a publishing page (the home page actually) but I encounter a stupid error that I don't understand. Here is the code I use:

var clientContext = new SP.ClientContext(siteNameAndUrl);		
var web = clientContext.get_web();				
var pubWeb = SP.Publishing.PublishingWeb.getPublishingWeb(clientContext, web);		
clientContext.load(web);		
clientContext.load(pubWeb);		
clientContext.executeQueryAsync(function(){			
	alert('OK');		
},handleError);	

When this code reaches the clientContext.load(pubWeb) I get the following error:

Object doesn't support property or method 'get_$y_0' 

Does any of you have a clue of what is going on and why I get this error?