[clang] [Clang] Fix a crash when using ast-dump=json (PR #70224)

[Tom Honermann via cfe-commits]

================
@@ -697,6 +697,8 @@ Miscellaneous Clang Crashes Fixed
   `Issue 64564 <https://github.com/llvm/llvm-project/issues/64564>`_
 - Fixed a crash when an ObjC ivar has an invalid type. See
   (`#68001 <https://github.com/llvm/llvm-project/pull/68001>`_)
+- Fixed a crash when ``-ast-dump=json`` was used for code using template
+  deduction guides.
----------------
tahonermann wrote:

```suggestion
- Fixed a crash when ``-ast-dump=json`` was used for code using class
  template deduction guides.
```

https://github.com/llvm/llvm-project/pull/70224