diff --git a/IDEHelper/Compiler/BfCompiler.cpp b/IDEHelper/Compiler/BfCompiler.cpp
index 121f1181..2575b7d3 100644
--- a/IDEHelper/Compiler/BfCompiler.cpp
+++ b/IDEHelper/Compiler/BfCompiler.cpp
@@ -364,6 +364,7 @@ BfCompiler::BfCompiler(BfSystem* bfSystem, bool isResolveOnly)
 	mInterfaceSlotCountChanged = false;
 	mLastHadComptimeRebuilds = false;
 	mHasComptimeRebuilds = false;
+	mDepsMayHaveDeletedTypes = false;	
 	
 	mHSPreserveIdx = 0;
 	mCompileLogFP = NULL;
@@ -482,7 +483,7 @@ BfCompiler::BfCompiler(BfSystem* bfSystem, bool isResolveOnly)
 	mContext = new BfContext(this);	
 	mCeMachine = new CeMachine(this);
 	mCurCEExecuteId = -1;
-	mLastMidCompileRefreshRevision = -1;
+	mLastMidCompileRefreshRevision = -1;	
 }
 
 BfCompiler::~BfCompiler()
@@ -2529,6 +2530,39 @@ void BfCompiler::UpdateDependencyMap(bool deleteUnusued, bool& didWork)
 	}
 
 	mContext->mQueuedSpecializedMethodRebuildTypes.Clear();
+	mDepsMayHaveDeletedTypes = false;
+}
+
+void BfCompiler::SanitizeDependencyMap()
+{
+	BfLogSysM("SanitizeDependencyMap\n");
+
+	for (auto type : mContext->mResolvedTypes)
+	{
+		if (type == NULL)
+			continue;
+		
+		auto depType = type->ToDependedType();			
+		if (depType == NULL)
+			continue;
+															
+		// Not combined with previous loop because PopulateType could modify typeInst->mDependencyMap
+		for (auto itr = depType->mDependencyMap.begin(); itr != depType->mDependencyMap.end();)
+		{
+			auto dependentType = itr->mKey;
+			auto depTypeInst = dependentType->ToTypeInstance();			
+			if (dependentType->IsDeleting())
+			{
+				BfLogSysM("SanitizeDependencyMap removing old dependent %p from %p\n", dependentType, depType);
+				itr = depType->mDependencyMap.erase(itr);				
+			}
+			else
+				++itr;
+		}
+	}	
+
+	mContext->RemoveInvalidWorkItems();
+	mDepsMayHaveDeletedTypes = false;
 }
 
 // When we are unsure of whether an old generic instance will survive, we RebuildType but don't put it in any worklist.
@@ -2538,7 +2572,7 @@ void BfCompiler::UpdateDependencyMap(bool deleteUnusued, bool& didWork)
 //   3) It stays undefined and we need to build it here
 void BfCompiler::ProcessPurgatory(bool reifiedOnly)
 {
-	BP_ZONE("BfCompiler::ProcessPuragory");	
+	BP_ZONE("BfCompiler::ProcessPurgatory");	
 
 	while (true)
 	{		
@@ -7432,7 +7466,13 @@ bool BfCompiler::DoCompile(const StringImpl& outputDirectory)
 	}
 		
 	ProcessPurgatory(false);
+	// ProcessPurgatory MAY cause type rebuilds which we need to handle
+	DoWorkLoop();
 	
+	BfLogSysM("Checking mDepsMayHaveDeletedTypes for SanitizeDependencyMap\n");
+	if (mDepsMayHaveDeletedTypes)
+		SanitizeDependencyMap();	
+
 	// Old Mark used modules	
 
 	if (!mIsResolveOnly)
@@ -7735,7 +7775,7 @@ bool BfCompiler::DoCompile(const StringImpl& outputDirectory)
 	if (didCancel)
 		mLastHadComptimeRebuilds = mHasComptimeRebuilds || mLastHadComptimeRebuilds;
 	else
-		mLastHadComptimeRebuilds = mHasComptimeRebuilds;
+		mLastHadComptimeRebuilds = mHasComptimeRebuilds;	
 
 	return !didCancel && !mHasQueuedTypeRebuilds;
 }
diff --git a/IDEHelper/Compiler/BfCompiler.h b/IDEHelper/Compiler/BfCompiler.h
index 14f7209a..ee5069f6 100644
--- a/IDEHelper/Compiler/BfCompiler.h
+++ b/IDEHelper/Compiler/BfCompiler.h
@@ -337,6 +337,7 @@ public:
 	bool mLastHadComptimeRebuilds;
 	bool mHasComptimeRebuilds;
 	bool mInInvalidState;
+	bool mDepsMayHaveDeletedTypes;
 	float mCompletionPct;
 	int mHSPreserveIdx;
 	BfModule* mLastAutocompleteModule;		
@@ -474,8 +475,9 @@ public:
 	BfIRFunction CreateLoadSharedLibraries(BfVDataModule* bfModule, Array<BfMethodInstance*>& dllMethods);
 	void GetTestMethods(BfVDataModule* bfModule, Array<TestMethod>& testMethods, HashContext& vdataHashCtx);
 	void EmitTestMethod(BfVDataModule* bfModule, Array<TestMethod>& testMethods, BfIRValue& retValue);
-	void CreateVData(BfVDataModule* bfModule);
+	void CreateVData(BfVDataModule* bfModule);	
 	void UpdateDependencyMap(bool deleteUnusued, bool& didWork);
+	void SanitizeDependencyMap();
 	void ProcessPurgatory(bool reifiedOnly);
 	bool VerifySlotNums();
 	bool QuickGenerateSlotNums();
diff --git a/IDEHelper/Compiler/BfContext.cpp b/IDEHelper/Compiler/BfContext.cpp
index a7a2ea2d..dc779256 100644
--- a/IDEHelper/Compiler/BfContext.cpp
+++ b/IDEHelper/Compiler/BfContext.cpp
@@ -1690,6 +1690,7 @@ void BfContext::DeleteType(BfType* type, bool deferDepRebuilds)
 	if (type->mRebuildFlags & BfTypeRebuildFlag_Deleted)
 		return;	
 	
+	mCompiler->mDepsMayHaveDeletedTypes = true;
 	mCompiler->mStats.mTypesDeleted++;
 
 	BfDependedType* dType = type->ToDependedType();
diff --git a/IDEHelper/Compiler/BfIRCodeGen.cpp b/IDEHelper/Compiler/BfIRCodeGen.cpp
index 4f26bf2c..99ccd65d 100644
--- a/IDEHelper/Compiler/BfIRCodeGen.cpp
+++ b/IDEHelper/Compiler/BfIRCodeGen.cpp
@@ -3959,7 +3959,13 @@ void BfIRCodeGen::HandleNextCmd()
 			CMD_PARAM(int, argIdx);
 			CMD_PARAM(String, name);
 
-			auto argItr = ((llvm::Function*)func)->arg_begin();
+			if (argIdx >= func->arg_size())
+			{
+				Fail("BfIRCmd_Func_SetParamName argIdx error");
+				break;
+			}
+
+			auto argItr = func->arg_begin();
 			for (int i = 1; i < argIdx; i++)
 				++argItr;
 			argItr->setName(name.c_str());