Fixed a PVS Studio static analyzer warning.

imgui.cpp

@@ -11524,8 +11524,9 @@ void ImGui::DockContextProcessDock(ImGuiContext* ctx, ImGuiDockRequest* req)
                     // Central node property needs to be moved to a leaf node, pick the last focused one.
                     // FIXME-DOCKING: If we had to transfer other flags here, what would the policy be?
                     ImGuiDockNode* last_focused_node = DockContextFindNodeByID(ctx, payload_node->LastFocusedNodeID);
+                    IM_ASSERT(last_focused_node != NULL);
                     ImGuiDockNode* last_focused_root_node = DockNodeGetRootNode(last_focused_node);
-                    IM_ASSERT(last_focused_node != NULL && last_focused_root_node == DockNodeGetRootNode(payload_node));
+                    IM_ASSERT(last_focused_root_node == DockNodeGetRootNode(payload_node));
                     last_focused_node->LocalFlags |= ImGuiDockNodeFlags_CentralNode;
                     node->LocalFlags &= ~ImGuiDockNodeFlags_CentralNode;
                     last_focused_root_node->CentralNode = last_focused_node;