[LyX/master] Fix null pointer warnings.

[Richard Kimberly Heck]

commit f4d5122a104204648d29fd2f7fa320db853ff580
Author: Richard Kimberly Heck <rikiheck at lyx.org>
Date:   Thu Feb 27 00:05:41 2020 -0500

    Fix null pointer warnings.
---
 src/frontends/qt/TocWidget.cpp |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/frontends/qt/TocWidget.cpp b/src/frontends/qt/TocWidget.cpp
index dcd9c4d..7a13d9d 100644
--- a/src/frontends/qt/TocWidget.cpp
+++ b/src/frontends/qt/TocWidget.cpp
@@ -118,7 +118,7 @@ Inset * TocWidget::itemInset() const
 		gui_view_.tocModels().currentItem(current_type_, index);
 	DocIterator const & dit = item.dit();
 
-	Inset * inset = 0;
+	Inset * inset = nullptr;
 	if (current_type_ == "label"
 		  || current_type_ == "graphics"
 		  || current_type_ == "citation"
@@ -408,7 +408,7 @@ void TocWidget::enableControls(bool enable)
 void TocWidget::updateView()
 {
 	if (!gui_view_.documentBufferView()) {
-		tocTV->setModel(0);
+		tocTV->setModel(nullptr);
 		depthSL->setMaximum(0);
 		depthSL->setValue(0);
 		setEnabled(false);