Poor user feedback when @action link returns an error

[rouilj]

Try the following:

1. log in as the demo user
2. Navigate to http://localhost:8080/demo/query?@template=chart&@charttype=barchart&@group0=creator&@group1=private_for
3. See a blank screen where the chart should be
4. look at the log for the tracker and notice that the @action=barchart url returns code 403.
5. navigate to the @action url that produces the svg: http://localhost:8080/demo/query?@action=barchart&@group=creator,private_for&@pagesize=50&@startwith=0
6. See this:

A few questions:

• Why is the error page not being shown in the embed where the svg should be? (update: I think it's the 403 return code.)
• How can we give the user better feedback?
• Is this condition a result of design decisions made earlier in the project?