[clang-tools-extra] [clang-tidy][NFC] Fix `bugprone-unchecked-optional-access` warnings in codebase (PR #170004)

[Baranov Victor via cfe-commits]

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@@ -600,15 +606,15 @@ void ClangTidyDiagnosticConsumer::checkFilters(SourceLocation Location,
 
 llvm::Regex *ClangTidyDiagnosticConsumer::getHeaderFilter() {
   if (!HeaderFilter)
-    HeaderFilter =
-        std::make_unique<llvm::Regex>(*Context.getOptions().HeaderFilterRegex);
+    HeaderFilter = std::make_unique<llvm::Regex>(
+        StringRef(Context.getOptions().HeaderFilterRegex.value_or("")));
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vbvictor wrote:

nit: `StringRef` seems redundant but may be?
Could you please check

https://github.com/llvm/llvm-project/pull/170004