Protect GetNextRef to avoid crashing if no scan context is initialize…

…d (either no GerFirstRef or GenNextRef returned null once)

Should fix #232

obse/obse/Commands_MiscReference.cpp

@@ -940,20 +940,27 @@ static const TESObjectCELL::ObjectListEntry* GetCellRefEntry(CellListVisitor vis
 
 	return entry;
 }
-
+/*
+TODO document and rework cell scans when it make sense. 
+Add additional protections for bad callers.
+*/
 static TESObjectREFR* CellScan(Script* scriptObj, TESObjectCELL* cellToScan = NULL, UInt32 formType = 0, UInt32 cellDepth = 0, bool getFirst = false, bool includeTaken = false, bool includeDeleted = false ,ProjectileFinder* projFinder = NULL)
 {
 	static std::map<UInt32, CellScanInfo> scanScripts;
 	UInt32 idx = scriptObj->refID;
 
 	if (getFirst)
 		scanScripts.erase(idx);
-
-	if (scanScripts.find(idx) == scanScripts.end())
+	bool isScriptUnRegistered = scanScripts.find(idx) == scanScripts.end();
+	if (isScriptUnRegistered  && cellToScan)
 	{
 		scanScripts[idx] = CellScanInfo(cellDepth, formType, includeTaken, includeDeleted , cellToScan);
 		scanScripts[idx].FirstCell();
 	}
+	else if (isScriptUnRegistered && cellToScan == nullptr) {
+		Console_Print("[ERROR], attempted to call GetNextRef after a Null reference, without reinit the cell scan with GetFirstRef. In Script %08X", scriptObj->refID);
+		return nullptr;
+	}
 
 	CellScanInfo* info = &(scanScripts[idx]);
 

obse_whatsnew.txt

@@ -16,6 +16,7 @@ xOBSE 22.10
 		- Avoid rare null pointer access in ShowRuntimeError (thanks @Fox2Code)
 		- Fix Menu{Tap/Hold/Release}Key commands not properly registering the button event for the UI.
 		- Fix xOBSE 22.7 regression for Useful House, now unmodified IR won't reset the stack extraDataList, possible if it was modified by another IR or directly by the engine.
+		- Fix CTD when GetNextRef is called in a script after returning a null reference, without a GetFirstRef call to reinitialize the scan.
 	Changes:
 		- Force C++20 Standard, modified some places for compliance
     API: