[clang] [SSAF][Extractor] Make hard errors in Extractors quiet (PR #201953)

[Balázs Benics via cfe-commits]

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@@ -107,6 +108,8 @@ PointerFlowMatcher::addEdges(Expected<EntityPointerLevelSet> &&LHS,
     return LHS.takeError();
   if (!RHS)
     return RHS.takeError();
+  if (RHS->empty())
+    return llvm::Error::success();
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steakhal wrote:

Technically, this is not needed, and we lose symmetry.
It's also an unexpected case, right? - In other words, on the happy path, this should never be empty.

https://github.com/llvm/llvm-project/pull/201953