[Feature Request] Client create_sandbox graceful failure when template not found

[brandonroyal]

As I understand, the current version of the python client times out when a template is provided as a parameter that doesn't exist. This is a suboptimal UX and it's fairly easy to mistype a template name

    template="test-template-does-not-exist", 
    namespace="default"
)```

I would expect the behavior to be something like a 404 with a friendly message suggesting that the template requested does not exist.