[clang] Crash on initialization

I compile this code with a crash:

```c
a = {{}, 1};
```

Assertion:

```console
/root/llvm-project/clang/include/clang/AST/Expr.h:5091: clang::Expr* clang::InitListExpr::getInit(unsigned int):
Assertion `Init < getNumInits() && "Initializer access out of range!"' failed.
```

The details can be found here: https://godbolt.org/z/Yc9nvE5de