From b8af429f0edecd9868447d35a0b1c7a3b5fd7e44 Mon Sep 17 00:00:00 2001
From: Lawrence Lee <billee@ucdavis.edu>
Date: Mon, 28 Sep 2020 22:17:49 -0700
Subject: [PATCH] Prevent null pointer access

Thanks to Ingo for fixing the segfault.
---
 rtengine/improccoordinator.cc | 2 +-
 rtengine/improccoordinator.h  | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/rtengine/improccoordinator.cc b/rtengine/improccoordinator.cc
index 72dfb0cd3..a88f6401f 100644
--- a/rtengine/improccoordinator.cc
+++ b/rtengine/improccoordinator.cc
@@ -364,7 +364,7 @@ void ImProcCoordinator::updatePreviewImage(int todo, bool panningRelatedChange)
             }
 
             imgsrc->getRAWHistogram(histRedRaw, histGreenRaw, histBlueRaw);
-            hist_raw_dirty = !hListener->updateHistogramRaw();
+            hist_raw_dirty = !(hListener && hListener->updateHistogramRaw());
 
             highDetailPreprocessComputed = highDetailNeeded;
 
diff --git a/rtengine/improccoordinator.h b/rtengine/improccoordinator.h
index d39fa3f9e..3020d68d5 100644
--- a/rtengine/improccoordinator.h
+++ b/rtengine/improccoordinator.h
@@ -469,7 +469,9 @@ public:
             hListener->setObservable(nullptr);
         }
         hListener = h;
-        h->setObservable(this);
+        if (h) {
+            h->setObservable(this);
+        }
     }
     void setAutoCamListener  (AutoCamListener* acl) override
     {