From 5b82b94c207267a8b8e67bfc3d58340cf39c3c64 Mon Sep 17 00:00:00 2001
From: Hugo Saint-Vignes <hugo.saint-vignes@numworks.com>
Date: Mon, 10 Aug 2020 11:55:26 +0200
Subject: [PATCH] [poincare] Prevent forbidden ChildAtIndex call in
 fraction_layout

Change-Id: I00d282a6dd3618f669aaeb0202d6495ae8035f12
---
 poincare/src/fraction_layout.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/poincare/src/fraction_layout.cpp b/poincare/src/fraction_layout.cpp
index ac035cf1b..2ecc79453 100644
--- a/poincare/src/fraction_layout.cpp
+++ b/poincare/src/fraction_layout.cpp
@@ -175,8 +175,10 @@ bool FractionLayoutNode::isCollapsable(int * numberOfOpenParenthesis, bool going
   int indexOfAbsorbingSibling = indexInParent + (goingLeft ? 1 : -1);
   assert(indexOfAbsorbingSibling >= 0 && indexOfAbsorbingSibling < p.numberOfChildren());
   Layout absorbingSibling = p.childAtIndex(indexOfAbsorbingSibling);
-  Layout absorbingChild = absorbingSibling.childAtIndex((goingLeft) ? absorbingSibling.leftCollapsingAbsorbingChildIndex() : absorbingSibling.rightCollapsingAbsorbingChildIndex());
-  return absorbingChild.type() == LayoutNode::Type::HorizontalLayout && absorbingChild.isEmpty();
+  if (absorbingSibling.numberOfChildren() > 0) {
+    absorbingSibling = absorbingSibling.childAtIndex((goingLeft) ? absorbingSibling.leftCollapsingAbsorbingChildIndex() : absorbingSibling.rightCollapsingAbsorbingChildIndex());
+  }
+  return absorbingSibling.type() == LayoutNode::Type::HorizontalLayout && absorbingSibling.isEmpty();
 }
 
 void FractionLayoutNode::didCollapseSiblings(LayoutCursor * cursor) {