small convenience fallback to id 0 in getattr (HH)

manual/luatex-nodes.tex

@@ -1937,7 +1937,8 @@ or, if no match is found, \type {nil}.
 \stopfunctioncall
 
 Tests if a node has an attribute with number \type {id} set. It returns the
-value, or, if no match is found, \type {nil}.
+value, or, if no match is found, \type {nil}. If no \type {id} is given then the
+zero attributes is assumed.
 
 \subsubsection{\type {node.find_attribute}}
 

source/texk/web2c/luatexdir/lua/lnodelib.c

@@ -3010,7 +3010,10 @@ static int lua_nodelib_get_attribute(lua_State * L)
         if (p != null) {
             p = vlink(p);
             if (p != null) {
-                int i = lua_tointeger(L, 2);
+                int i = 0;
+                if (lua_gettop(L) > 1) {
+                    i = lua_tointeger(L, 2);
+                }
                 while (p != null) {
                     if (attribute_id(p) == i) {
                         int ret = attribute_value(p);
@@ -3082,7 +3085,10 @@ static int lua_nodelib_direct_get_attribute(lua_State * L)
         if (p != null) {
             p = vlink(p);
             if (p != null) {
-                int i = lua_tointeger(L, 2);
+                int i = 0;
+                if (lua_gettop(L) > 1) {
+                    i = lua_tointeger(L, 2);
+                }
                 while (p != null) {
                     if (attribute_id(p) == i) {
                         int ret = attribute_value(p);

source/texk/web2c/luatexdir/luatex_svnversion.h

-#define luatex_svn_revision 6771
+#define luatex_svn_revision 6772