2 files changed, 8 insertions, 4 deletions
diff --git a/Userland/Applications/SystemMonitor/ProcessModel.cpp b/Userland/Applications/SystemMonitor/ProcessModel.cpp
index 98f31612de..03322e6d24 100644
--- a/Userland/Applications/SystemMonitor/ProcessModel.cpp
+++ b/Userland/Applications/SystemMonitor/ProcessModel.cpp
@@ -344,7 +344,9 @@ GUI::ModelIndex ProcessModel::index(int row, int column, GUI::ModelIndex const&
         if (row >= static_cast<int>(m_processes.size()))
             return {};
         auto corresponding_thread = m_processes[row].main_thread();
-        return create_index(row, column, corresponding_thread.ptr());
+        if (!corresponding_thread.has_value())
+            return {};
+        return create_index(row, column, corresponding_thread.release_value().ptr());
     }
     // Thread under process.
     auto const& parent_thread = *static_cast<Thread const*>(parent.internal_data());
@@ -375,8 +377,10 @@ GUI::ModelIndex ProcessModel::parent_index(GUI::ModelIndex const& index) const
         return {};
     // FIXME: We can't use first_matching here (not even a const version) because Optional cannot contain references.
     auto const& parent = thread.current_state.process;
+    if (!parent.main_thread().has_value())
+        return {};
 
-    return create_index(m_processes.find_first_index(parent).release_value(), index.column(), parent.main_thread().ptr());
+    return create_index(m_processes.find_first_index(parent).release_value(), index.column(), parent.main_thread().value().ptr());
 }
 
 Vector<GUI::ModelIndex> ProcessModel::matches(StringView searching, unsigned flags, GUI::ModelIndex const&)
diff --git a/Userland/Applications/SystemMonitor/ProcessModel.h b/Userland/Applications/SystemMonitor/ProcessModel.h
index 93f7618f46..d8daecbeef 100644
--- a/Userland/Applications/SystemMonitor/ProcessModel.h
+++ b/Userland/Applications/SystemMonitor/ProcessModel.h
@@ -210,9 +210,9 @@ private:
             return this->pid == other.pid;
         }
 
-        NonnullRefPtr<Thread> main_thread() const
+        Optional<NonnullRefPtr<Thread>> main_thread() const
         {
-            return *threads.first_matching([this](auto const thread) { return thread->current_state.tid == pid; }).value();
+            return threads.first_matching([this](auto const thread) { return thread->current_state.tid == pid; });
         }
 
         // Return anything but the main thread; therefore, valid indices are anything up to threads.size()-1 exclusive.