class IEEE754Single(data.Struct):
    fraction: 23
    exponent:  8 = 0x7f
    sign:      1

class SomeStruct(data.Struct):
    options: Array[IEEE754Single, 2]

some_struct = Signal(SomeStruct, reset={
    "options": [
        {"fraction": 0x1FFFF7, "exponent": 0x7E, "sign": 0},
        {"fraction": 0x1FFFF7, "exponent": 0x7E, "sign": 1}
    ]
})
```
gives
```
  File "/lib/python3.11/site-packages/amaranth/hdl/ast.py", line 1144, in __init__
    raise TypeError("Reset value must be a constant initializer of {!r}"
TypeError: Reset value must be a constant initializer of <class 'SomeStruct'>