tree: explicitly use node type static

Fixes #104

tree.go

diff --git a/tree.go b/tree.go
index faf5fdc..eeadec9 100644
--- a/tree.go
+++ b/tree.go
@@ -106,6 +106,7 @@
 				child := node{
 					path:      n.path[i:],
 					wildChild: n.wildChild,
+					nType:     static,
 					indices:   n.indices,
 					children:  n.children,
 					handle:    n.handle,