Replacing rvrv code pattern

[quffaro]

This PR addresses a TODO in acsets.jl for replacing an array of incident calls with an ACSet query.

chain_starts = (From(:Op1) |> 
  Where(:src, d[:res] ∪ d[:sum] ∪ filter(!isnothing, infer_states(d))) |
  Where(:src, From(:Op1=>:tgt) |> Where(:op1, collect(black_list))))(d)

This PR depends on FunSQL-like querying an ACSet.

[lukem12345]

@quffaro The query is failing due to trying to read something at index 1 from an empty buffer.