Re-add accidentally removed code; fixes precommit CI test

Author: AaronBallman

clang/lib/Sema/SemaExceptionSpec.cpp

@@ -1211,7 +1211,8 @@ CanThrowResult Sema::canThrow(const Stmt *S) {
         if (const RecordType *RT = DTy->getAs<RecordType>()) {
           const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
           const CXXDestructorDecl *DD = RD->getDestructor();
-          CT = mergeCanThrow(CT, canCalleeThrow(*this, DE, DD));
+          if (DD)
+            CT = mergeCanThrow(CT, canCalleeThrow(*this, DE, DD));
         }
         if (CT == CT_Can)
           return CT;