[clang][module] clang assertion on ``CheckPoint >= Buff->getBufferStart() && CheckPoint <= Buff->getBufferEnd()' ` when compile options are not configured

```cxx
#pragma clang module build A
module A {}
#pragma clang module contents
#pragma clang module begin A
template auto f() { return []{}; }
#pragma clang module end
#pragma clang module endbuild

#pragma clang module build B
struct Outer {
struct Inner {
Inner() {}
Function f = []{};
};
Outer(Inner = Inner());
};

inline void use_nested_2() { Outer o; }
#pragma clang module end
#pragma clang module endbuild

inline auto q() { return []{}; }
inline auto x3() { return q(); }

#pragma clang module import B
#pragma clang module import C
using T = decltype(x1);
using T = decltype(y1);

using U = decltype(x2);
using U = decltype(y2);

using V = decltype(x3);
using V = decltype(y3);

#pragma clang module import A
void (*p)() = f();

void use_nested() {
use_nested_1();
use_nested_2();
}
```
https://godbolt.org/z/Poxq1zM5j
seem to be introduced since clang21.1.0, not reproducable in clang20.1.0
Occurs on both assert and non assert version, and it triggers two assertions at the same time.
It is a bit weird that whenever the C++ version is configured in compile option, even if in that version module is not supported, it doesn't crash,