table: ensure NameTree::lookup(tableEntry) does not return nullptr

NameTree::lookup(tableEntry) is always equivalent to NameTree::lookup(Name).
NameTree::getEntry(tableEntry) should be used when inserting new name tree entry is undesired.

refs #3687

Change-Id: I0b17cd07dde83341976cfe66c85855dfb2fa6e89
diff --git a/daemon/table/strategy-choice.hpp b/daemon/table/strategy-choice.hpp
index a238761..1388cbb 100644
--- a/daemon/table/strategy-choice.hpp
+++ b/daemon/table/strategy-choice.hpp
@@ -167,7 +167,7 @@
                  fw::Strategy& newStrategy);
 
   fw::Strategy&
-  findEffectiveStrategy(const name_tree::Entry* nte) const;
+  findEffectiveStrategy(const name_tree::Entry& nte) const;
 
 private:
   NameTree& m_nameTree;