Fixed size array assignment causes assert

Description
A compiler assert is hit when attempting to do a fixed array value assignment. I would expect a compiler error to be emitted instead, with a clean exit.

Steps to Reproduce

https://godbolt.org/z/jcr6WT8b6

Compile the following minimum repro with dxc -T as_6_5 -E as_main bug.hlsl

struct MS_Payload {
    float2 uvs[4];
};

[NumThreads(1, 1, 1)]
void as_main() {

    float2 UVS[4] = {
        float2(0, 0),
        float2(0, 1),
        float2(1, 1),
        float2(1, 0),
    };

    MS_Payload payload;
    payload.uvs = UVS; // <-- here

    DispatchMesh(1, 1, 1, payload);
}

Actual Behavior
Yields error: cast<X>() argument of incompatible type!

Stack trace when used via libdxcompiler.dylib:

Environment

./dxc --version
libdxcompiler.dylib: 1.9(dev;5011-dc85cd71)

macOS Sequoia 15.6

Begin with the Godbolt minimum repro and run it using dxc -T as_6_5 -E as_main bug.hlsl to reproduce the assertion. Trace the reported cast<X>() failure in the compiler, then verify that the fixed-array assignment produces a clean compiler diagnostic and exit instead of asserting.