Add test for calling each on empty vec
Add test for calling each on empty vec

This patch adds a test for calling the "each helper" on a vector that is
empty, but without an `else` block in the template.

This fails with a "variable not found", which is misleading.

Signed-off-by: Matthias Beyer <1d6e1cf70ec6f9ab28d3ea4b27a49a77654d370e@beyermatthias.de>

sunng87/handlebars-rust,sunng87/handlebars-rust