way.is_closed() should only be called when there are way nodes

When you are feeding ways without nodes to osm2pgsql, which should never
happen in normal operation, osm2pgsql will break without this check.

Author: joto

src/output-flex.cpp

@@ -191,7 +191,8 @@ static void push_osm_object_to_lua_stack(lua_State *lua_state,
 
     if (object.type() == osmium::item_type::way) {
         auto const &way = static_cast<osmium::Way const &>(object);
-        luaX_add_table_bool(lua_state, "is_closed", way.is_closed());
+        luaX_add_table_bool(lua_state, "is_closed",
+                            !way.nodes().empty() && way.is_closed());
         luaX_add_table_array(lua_state, "nodes", way.nodes(),
                              [&](osmium::NodeRef const &wn) {
                                  lua_pushinteger(lua_state, wn.ref());

src/output-gazetteer.cpp

@@ -137,7 +137,7 @@ bool output_gazetteer_t::process_way(osmium::Way *way)
 
     // Get the geometry of the object.
     geom::geometry_t geom;
-    if (way->is_closed()) {
+    if (!way->nodes().empty() && way->is_closed()) {
         geom = geom::transform(geom::create_polygon(*way), *m_proj);
     }
     if (geom.is_null()) {

src/output-pgsql.cpp

@@ -61,7 +61,7 @@ static double calculate_area(bool reproject_area,
 void output_pgsql_t::pgsql_out_way(osmium::Way const &way, taglist_t *tags,
                                    bool polygon, bool roads)
 {
-    if (polygon && way.is_closed()) {
+    if (polygon && !way.nodes().empty() && way.is_closed()) {
         auto const geom = geom::create_polygon(way);
         auto const projected_geom = geom::transform(geom, *m_proj);