Index: lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
+++ lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
@@ -693,6 +693,8 @@
         !Param->getType()->isReferenceType())
       continue;
 
+    assert(ArgExpr && "cannot get the type of a NULL expression");
+
     NullConstraint Nullness = getNullConstraint(*ArgSVal, State);
 
     Nullability RequiredNullability =
Index: lib/StaticAnalyzer/Core/PlistDiagnostics.cpp
===================================================================
--- lib/StaticAnalyzer/Core/PlistDiagnostics.cpp
+++ lib/StaticAnalyzer/Core/PlistDiagnostics.cpp
@@ -294,9 +294,8 @@
   SmallVector<FileID, 10> Fids;
   const SourceManager* SM = nullptr;
 
-  if (!Diags.empty())
-    SM = &Diags.front()->path.front()->getLocation().getManager();
-
+  assert(!Diags.empty() && "cannot iterate through empty PathDiagnostic");
+  SM = &Diags.front()->path.front()->getLocation().getManager();
 
   for (std::vector<const PathDiagnostic*>::iterator DI = Diags.begin(),
        DE = Diags.end(); DI != DE; ++DI) {