[clang-tools-extra] [clang][dataflow]Use cast_or_null instead cast to prevent crash (PR #68510)

[Piotr Zegar via cfe-commits]

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@@ -202,6 +202,10 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/reserved-identifier>` check, so that it does not
   warn on macros starting with underscore and lowercase letter.
 
+- Improved :doc:`bugprone-unchecked-optional-access
+  <clang-tidy/checks/bugprone/unchecked-optional-access>` check, use `cast_or_null`
+  instead `cast` so that it does not crash during handling of optional values.
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PiotrZSL wrote:

information about cast or cast_or_null is not needed here, this is just info for users who had this check crashed, and decided to disable it, to consider re-enabling it or even testing it again on their projects.

https://github.com/llvm/llvm-project/pull/68510