[LyX/master] Check whether MathRow exists when computing caret metrics

[Jean-Marc Lasgouttes]

commit 7eecab590280892d1dab85298366d0033bbf0e39
Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
Date:   Sat Sep 2 17:15:20 2023 +0200

    Check whether MathRow exists when computing caret metrics
    
    Fixes bug #12888.
---
 src/BufferView.cpp |    8 +++++++-
 src/BufferView.h   |    2 ++
 2 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/src/BufferView.cpp b/src/BufferView.cpp
index 9ec5df3..4531bda 100644
--- a/src/BufferView.cpp
+++ b/src/BufferView.cpp
@@ -435,6 +435,12 @@ CoordCache const & BufferView::coordCache() const
 }
 
 
+bool BufferView::hasMathRow(MathData const * cell) const
+{
+	return d->math_rows_.find(cell) != d->math_rows_.end();
+}
+
+
 MathRow const & BufferView::mathRow(MathData const * cell) const
 {
 	auto it = d->math_rows_.find(cell);
@@ -3323,7 +3329,7 @@ bool BufferView::paragraphVisible(DocIterator const & dit) const
 void BufferView::caretPosAndDim(Point & p, Dimension & dim) const
 {
 	Cursor const & cur = cursor();
-	if (cur.inMathed()) {
+	if (cur.inMathed() && hasMathRow(&cur.cell())) {
 		MathRow const & mrow = mathRow(&cur.cell());
 		dim = mrow.caret_dim;
 	} else {
diff --git a/src/BufferView.h b/src/BufferView.h
index b64b431..f816eda 100644
--- a/src/BufferView.h
+++ b/src/BufferView.h
@@ -322,6 +322,8 @@ public:
 	CoordCache const & coordCache() const;
 
 	///
+	bool hasMathRow(MathData const * cell) const;
+	///
 	MathRow const & mathRow(MathData const * cell) const;
 	///
 	void setMathRow(MathData const * cell, MathRow const & mrow);