Refactor code to make it easier to do 'nopredict' inside of any function without having a dependency on world model.

luprex/cpp/core/luastack.cpp

@@ -466,6 +466,24 @@ void LuaStack::setvisited(LuaSlot tab, bool visited) const {
     lua_modflagbits(L_, tab.index(), 0x0010, visited ? 0x0010 : 0);
 }
 
+WorldType LuaStack::world_type() const {
+    lua_pushstring(L_, "worldtype");
+    lua_rawget(L_, LUA_REGISTRYINDEX);
+    lua_Integer n = lua_tointeger(L_, -1);
+    lua_pop(L_, 1);
+    assert(n != 0);
+    return (WorldType)n;
+}
+
+void LuaStack::guard_nopredict(const char *fn) {
+    if (lua_isyieldable(L_)) {
+        if (!is_authoritative()) {
+            lua_yield(L_, 0);
+            luaL_error(L_, "unexplained nopredict failure in %s", fn);
+        }
+    }
+}
+
 LuaKeywordParser::LuaKeywordParser(lua_State *L, int slot) {
     L_ = L;
     slot_ = slot;