Fix crash IndexedLineSet (#6359)

* Fix crash indexedLineSet

* changelog

* Update changelog-r2023.md

Author: Benjamin Délèze

docs/reference/changelog-r2023.md

@@ -11,6 +11,7 @@ Released on XXX XXth, 2023.
     - Fixed Webots and libController version comparison not to take revisions into account ([#6315](https://github.com/cyberbotics/webots/pull/6315)).
     - Fixed translation, rotation and scale displayed in the Position tab of the Node viewer in the scene tree ([#6309](https://github.com/cyberbotics/webots/pull/6309)).
     - Replaced the [Mesh](mesh.md) bounding object of the ROSbot XL by [Boxes](box.md) ([#6326](https://github.com/cyberbotics/webots/pull/6326)).
+    - Fixed a crash when [IndexedLineSet](indexedlineset.md) has `coord` but no `coordIndex` ([#6359](https://github.com/cyberbotics/webots/pull/6359)).
 
 ## Webots R2023b
 Released on June 28th, 2023.

src/webots/nodes/WbIndexedLineSet.cpp

@@ -228,7 +228,7 @@ void WbIndexedLineSet::recomputeBoundingSphere() const {
   assert(mBoundingSphere);
   mBoundingSphere->empty();
 
-  if (!coord())
+  if (!coord() || mCoordIndex->isEmpty())
     return;
 
   const WbMFVector3 &points = coord()->point();