[clang] [clang] Fix crash when compiling error with invalid decl (PR #77893)

[Shafik Yaghmour via cfe-commits]

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@@ -40,7 +40,11 @@ static_assert(
     "Type is insufficiently aligned");
 
 APValue::LValueBase::LValueBase(const ValueDecl *P, unsigned I, unsigned V)
-    : Ptr(P ? cast<ValueDecl>(P->getCanonicalDecl()) : nullptr), Local{I, V} {}
+    : Ptr(P ? cast<ValueDecl>(P->getCanonicalDecl()->isInvalidDecl()
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shafik wrote:

Not clear to me why we check `isInvalidDecl()` here

https://github.com/llvm/llvm-project/pull/77893