AiEscortCell complains if no cell was given or cell does not exist

apps/openmw/mwscript/aiextensions.cpp

@@ -1,5 +1,8 @@
 #include "aiextensions.hpp"
 
+#include <stdexcept>
+#include <iostream>
+
 #include <components/compiler/extensions.hpp>
 #include <components/compiler/opcodes.hpp>
 
@@ -8,6 +11,7 @@
 #include <components/interpreter/opcodes.hpp>
 
 #include "../mwworld/class.hpp"
+#include "../mwworld/esmstore.hpp"
 
 #include "../mwmechanics/creaturestats.hpp"
 #include "../mwmechanics/aiactivate.hpp"
@@ -18,13 +22,11 @@
 
 #include "../mwbase/environment.hpp"
 #include "../mwbase/world.hpp"
+#include "../mwbase/mechanicsmanager.hpp"
 
 #include "interpretercontext.hpp"
 #include "ref.hpp"
 
-#include <iostream>
-
-#include "../mwbase/mechanicsmanager.hpp"
 
 namespace MWScript
 {
@@ -144,6 +146,11 @@ namespace MWScript
                     // discard additional arguments (reset), because we have no idea what they mean.
                     for (unsigned int i=0; i<arg0; ++i) runtime.pop();
 
+                    if (cellID.empty())
+                        throw std::runtime_error("AiEscortCell: no cell ID given");
+
+                    MWBase::Environment::get().getWorld()->getStore().get<ESM::Cell>().find(cellID);
+
                     MWMechanics::AiEscort escortPackage(actorID, cellID, static_cast<int>(duration), x, y, z);
                     ptr.getClass().getCreatureStats (ptr).getAiSequence().stack(escortPackage, ptr);