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

[via cfe-commits]

elizabethandrews wrote:

I apologize for the force push. I had a strange Git error I was trying to get rid of.  I also squashed my commits for the same reason. It doesn't look like it has helped though. I see the first test bot checking formatting fails with

```
Run python llvm/utils/git/code-format-helper.py \
Running: git-clang-format --diff aa30018e66105b4a8bd0947e35d1946d[24](https://github.com/llvm/llvm-project/actions/runs/6698182261/job/18199674028?pr=70224#step:8:25)2cd99c f4559a402d92fd6ab394b586b1c5f3f6d740c3a8 -- clang/lib/AST/JSONNodeDumper.cpp clang/test/AST/ast-dump-template-decls-json.cpp
error: 'aa30018e66105b4a8bd0947e35d1946d242cd99c' is not a commit
error: clang-format exited with code 2
error: some formatters failed: clang-format
Error: Process completed with exit code 1.
```

I have no idea why this is happening.

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