From c2da881010e1d286f5ceb8b0c311ccf8e891246b Mon Sep 17 00:00:00 2001
From: James Turner <zakalawe@mac.com>
Date: Sat, 25 Mar 2017 14:28:30 +0000
Subject: [PATCH] Fix a crash in NavList

(Tests are good)
---
 src/Navaids/navlist.cxx | 2 +-
 src/Navaids/navlist.hxx | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Navaids/navlist.cxx b/src/Navaids/navlist.cxx
index 9b0c911de..50c07a2e9 100644
--- a/src/Navaids/navlist.cxx
+++ b/src/Navaids/navlist.cxx
@@ -203,7 +203,7 @@ FGNavRecordRef FGNavList::findByFreq( double freq,
     
   BOOST_FOREACH(PositionedID id, stations) {
     FGNavRecordRef station = FGPositioned::loadById<FGNavRecord>(id);
-    if (!filter->pass(station)) {
+    if (filter && !filter->pass(station)) {
       continue;
     }
     
diff --git a/src/Navaids/navlist.hxx b/src/Navaids/navlist.hxx
index c10b7e3b7..0cdfeb74a 100644
--- a/src/Navaids/navlist.hxx
+++ b/src/Navaids/navlist.hxx
@@ -93,7 +93,7 @@ public:
       * so a position must be specified.
       */
     static FGNavRecordRef findByFreq( double freq, const SGGeod& position,
-                                   TypeFilter* filter = NULL);
+                                   TypeFilter* filter = nullptr);
 
     /**
      * Overloaded version above - no positioned supplied so can be used with