[clang] [NFC] Avoid potential null dereference. (PR #127017)

[Balazs Benics via cfe-commits]

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@@ -314,6 +314,7 @@ void MacOSKeychainAPIChecker::checkPreStmt(const CallExpr *CE,
     RegionArgIsBad = true;
   }
 
+  assert(ArgSM);
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steakhal wrote:

I'm okay with this assert.
It shouldn't change much though because the very next lookup would fail if this was a null pointer because we never store entries for null pointers.
Thanks for the assert!

https://github.com/llvm/llvm-project/pull/127017