Unable to infer ranges for indices `i`, in deeply nested `r[k][j][i]`

Nobody has claimed this yet.

Consider the MWE:

```julia
using TensorCast # 0.4.8

r = fill(fill(ones(3), 5), 7)

function f(r)
@cast _[i, j ⊗ k] := r[k].a[j][i]
end
```

Ideally `f(r)` should give a 3 x 35 matrix, but I get
```julia
ERROR: LoadError: unable to infer ranges for indices i
@cast _[i, j ⊗ k] := ((r[k]).a[j])[i]
@ Main REPL[22]:2
Stacktrace:
[1] sizeinfer(store::@NamedTuple{dict::Dict{Any, Any}, assert::Vector{Any}, mustassert::Vector{Any}, seen::Vector{Any}, need::Vector{Any}, top::Vector{Any}, main::Vector{Any}}, call::TensorCast.CallInfo)
@ TensorCast ~/.julia/packages/TensorCast/fctFg/src/macro.jl:1143
[2] findsizes(store::@NamedTuple{dict::Dict{Any, Any}, assert::Vector{Any}, mustassert::Vector{Any}, seen::Vector{Any}, need::Vector{Any}, top::Vector{Any}, main::Vector{Any}}, call::TensorCast.CallInfo)
@ TensorCast ~/.julia/packages/TensorCast/fctFg/src/macro.jl:1092
[3] _macro(exone::Expr, extwo::Nothing, exthree::Nothing; call::TensorCast.CallInfo, dict::Dict{Any, Any})
@ TensorCast ~/.julia/packages/TensorCast/fctFg/src/macro.jl:211
[4] _macro
@ ~/.julia/packages/TensorCast/fctFg/src/macro.jl:154 [inlined]
[5] var"@cast"(__source__::LineNumberNode, __module__::Module, exs::Vararg{Any})
@ TensorCast ~/.julia/packages/TensorCast/fctFg/src/macro.jl:74
in expression starting at REPL[22]:2
```

Is it possible to make this work somehow?

Start by running the MWE from the issue with TensorCast 0.4.8 and inspect src/macro.jl around sizeinfer and findsizes, which appear in the stack trace. Trace how ranges are inferred through the nested r[k].a[j][i] expression. Done means the @cast call works and produces the expected 3 × 35 matrix.

Written by the indexing model from the issue text.