From f596fd2b98f710b14af9bb53051524efd46e35ae Mon Sep 17 00:00:00 2001
From: Tim Adye <Tim.Adye@cern.ch>
Date: Wed, 14 Jun 2023 18:37:46 +0100
Subject: [PATCH] restore OutOfBounds check. assert if neighbors array not
 fully filled.

---
 Core/include/Acts/MagneticField/InterpolatedBFieldMap.hpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Core/include/Acts/MagneticField/InterpolatedBFieldMap.hpp b/Core/include/Acts/MagneticField/InterpolatedBFieldMap.hpp
index 28f64f8ebff..3e18a1da061 100644
--- a/Core/include/Acts/MagneticField/InterpolatedBFieldMap.hpp
+++ b/Core/include/Acts/MagneticField/InterpolatedBFieldMap.hpp
@@ -202,11 +202,17 @@ class InterpolatedBFieldMap : public InterpolatedMagneticField {
     std::array<Vector3, nCorners> neighbors;
     const auto& cornerIndices = m_cfg.grid.closestPointsIndices(gridPosition);
 
+    if (!isInsideLocal(gridPosition)) {
+      return MagneticFieldError::OutOfBounds;
+    }
+
     size_t i = 0;
     for (size_t index : cornerIndices) {
       neighbors.at(i++) = m_cfg.transformBField(m_cfg.grid.at(index), position);
     }
 
+    assert(i == nCorners);
+
     return FieldCell(lowerLeft, upperRight, std::move(neighbors));
   }