class Mustache::ContextMiss

By default it is not raised. See Mustache.raise_on_context_miss.
your template contains a ‘{{music}}` tag this exception will be raised.
For example, if your View class does not respond to `music` but
set to true.
in the current context if `Mustache#raise_on_context_miss?` is
A ContextMiss is raised whenever a tag’s target can not be found