[clang] [clang][bytecode] Fix reading union template parameter object (PR #179899)

[Timm Baeder via cfe-commits]

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@@ -5069,14 +5069,30 @@ bool Compiler<Emitter>::visitAPValueInitializer(const APValue &Val,
   }
   if (Val.isUnion()) {
     const FieldDecl *UnionField = Val.getUnionField();
-    const Record *R = this->getRecord(UnionField->getParent());
+    if (!UnionField)
+      // no active fields
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tbaederr wrote:

```suggestion
```

https://github.com/llvm/llvm-project/pull/179899