From 73336c9f9a16c681d64703b2a5d70963fbc4ecb1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Franz=20P=C3=B6schel?= <franz.poeschel@gmail.com>
Date: Wed, 31 Jan 2024 15:09:25 +0100
Subject: [PATCH] Fix nullpointer issue

---
 include/openPMD/snapshots/ContainerImpls.hpp |  2 +-
 src/snapshots/ContainerImpls.cpp             | 24 ++++++++++++++++++--
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/include/openPMD/snapshots/ContainerImpls.hpp b/include/openPMD/snapshots/ContainerImpls.hpp
index adc14c1be7..510fe1b768 100644
--- a/include/openPMD/snapshots/ContainerImpls.hpp
+++ b/include/openPMD/snapshots/ContainerImpls.hpp
@@ -20,7 +20,7 @@ class StatefulSnapshotsContainer : public AbstractSnapshotsContainer
     auto get() const -> StatefulIterator const *;
 
 public:
-    using AbstractSnapshotsContainer::currentIteration;
+    auto currentIteration() -> std::optional<value_type *> override;
     auto currentIteration() const -> std::optional<value_type const *> override;
 
     auto begin() -> iterator override;
diff --git a/src/snapshots/ContainerImpls.cpp b/src/snapshots/ContainerImpls.cpp
index 11524d5eec..5719d125d1 100644
--- a/src/snapshots/ContainerImpls.cpp
+++ b/src/snapshots/ContainerImpls.cpp
@@ -39,10 +39,29 @@ auto StatefulSnapshotsContainer::get() const -> StatefulIterator const *
 {
     return m_bufferedIterator.value_or(nullptr);
 }
+auto StatefulSnapshotsContainer::currentIteration()
+    -> std::optional<value_type *>
+{
+    if (auto it = get(); it)
+    {
+        return it->peekCurrentlyOpenIteration();
+    }
+    else
+    {
+        return nullptr;
+    }
+}
 auto StatefulSnapshotsContainer::currentIteration() const
     -> std::optional<value_type const *>
 {
-    return get()->peekCurrentlyOpenIteration();
+    if (auto it = get(); it)
+    {
+        return it->peekCurrentlyOpenIteration();
+    }
+    else
+    {
+        return nullptr;
+    }
 }
 auto StatefulSnapshotsContainer::begin() -> iterator
 {
@@ -93,7 +112,8 @@ auto StatefulSnapshotsContainer::rend() const -> const_iterator
 
 bool StatefulSnapshotsContainer::empty() const
 {
-    return get()->operator bool();
+    auto it = get();
+    return (!it) || it->operator bool();
 }
 
 auto StatefulSnapshotsContainer::at(key_type const &) const