Invalid template causes templatecheck to panic

[wttw]

When running templatecheck v0.7.0 with the attached sample it panics, after dereferencing a nil reflect.Type in indirectType().

The template has a bug, it doesn't pass a parameter into the subtemplate "cross", so I'd expect an error response.

main.go.txt

(This found several bugs in a set of templates I've been using in production for weeks, which I wouldn't have found without it. Definitely a useful library.)