From 9ff6d1b786c52d0aae485507d96ea67f3171b9fd Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Fri, 31 Jul 2020 01:04:43 +0200
Subject: [PATCH] Fix crash on too-early update of closed caption dialog.

---
 src/wx/closed_captions_dialog.cc | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/wx/closed_captions_dialog.cc b/src/wx/closed_captions_dialog.cc
index 625652b8c..4519c4b7c 100644
--- a/src/wx/closed_captions_dialog.cc
+++ b/src/wx/closed_captions_dialog.cc
@@ -165,22 +165,23 @@ ClosedCaptionsDialog::update ()
 	if (!_current && !_tracks.empty()) {
 		/* We have no current one: get another */
 		shared_ptr<Butler> butler = _butler.lock ();
-		DCPOMATIC_ASSERT (butler);
 		DCPOMATIC_ASSERT (_track->GetSelection() >= 0);
 		DCPOMATIC_ASSERT (_track->GetSelection() < int(_tracks.size()));
 		DCPTextTrack track = _tracks[_track->GetSelection()];
-		while (true) {
-			optional<TextRingBuffers::Data> d = butler->get_closed_caption ();
-			if (!d) {
-				break;
-			}
-			if (d->track == track) {
-				_current = d;
-				break;
+		if (butler) {
+			while (true) {
+				optional<TextRingBuffers::Data> d = butler->get_closed_caption ();
+				if (!d) {
+					break;
+				}
+				if (d->track == track) {
+					_current = d;
+					break;
+				}
 			}
-		}
 
-		_current_in_lines = false;
+			_current_in_lines = false;
+		}
 	}
 
 	if (_current && _current->period.contains(time)) {
-- 
2.30.2