[TensorAlgebra] [BUG] TensorAlgebra.contract fails for full contraction

[ogauthe]

TensorAlgebra.contract crashes when one tries to contract all axes from exactly one input.

using NDTensors.TensorAlgebra
mat = ones((1,1))
vec = ones((1,))
TensorAlgebra.contract(mat, (1, 2), mat, (2, 3))  # OK
TensorAlgebra.contract(mat, (1, 2), mat, (1, 2))  # OK
TensorAlgebra.contract(vec, (1,), vec, (1,))  # OK
TensorAlgebra.contract(mat, (1, 2), vec, (2,))  # MethodError
TensorAlgebra.contract(vec, (1,), mat, (1,2))  # MethodError

ERROR: MethodError: no method matching output_axes(::typeof(NDTensors.TensorAlgebra.contract), ::NDTensors.TensorAlgebra.BlockedPermutation{…}, ::Vector{…}, ::NDTensors.TensorAlgebra.BlockedPermutation{…}, ::Matrix{…}, ::NDTensors.TensorAlgebra.BlockedPermutation{…}, ::Bool)

Closest candidates are:
  output_axes(::typeof(NDTensors.TensorAlgebra.contract), ::NDTensors.TensorAlgebra.BlockedPermutation{0, Length, Blocks} where {Length, Blocks<:Tuple{}}, ::AbstractArray, ::NDTensors.TensorAlgebra.BlockedPermutation{1, Length, Blocks} where {Length, Blocks<:Tuple{Tuple{Vararg{Int64}}}}, ::AbstractArray, ::NDTensors.TensorAlgebra.BlockedPermutation{1, Length, Blocks} where {Length, Blocks<:Tuple{Tuple{Vararg{Int64}}}}, ::Number)
   @ NDTensors ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/allocate_output.jl:23
  output_axes(::typeof(NDTensors.TensorAlgebra.contract), ::NDTensors.TensorAlgebra.BlockedPermutation{2, Length, Blocks} where {Length, Blocks<:Tuple{Tuple{Vararg{Int64}}, Tuple{Vararg{Int64}}}}, ::AbstractArray, ::NDTensors.TensorAlgebra.BlockedPermutation{2, Length, Blocks} where {Length, Blocks<:Tuple{Tuple{Vararg{Int64}}, Tuple{Vararg{Int64}}}}, ::AbstractArray, ::NDTensors.TensorAlgebra.BlockedPermutation{2, Length, Blocks} where {Length, Blocks<:Tuple{Tuple{Vararg{Int64}}, Tuple{Vararg{Int64}}}}, ::Number)
   @ NDTensors ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/allocate_output.jl:5
  output_axes(::typeof(NDTensors.TensorAlgebra.contract), ::NDTensors.TensorAlgebra.BlockedPermutation{0, Length, Blocks} where {Length, Blocks<:Tuple{}}, ::AbstractArray, ::NDTensors.TensorAlgebra.BlockedPermutation{1, Length, Blocks} where {Length, Blocks<:Tuple{Tuple{Vararg{Int64}}}}, ::AbstractArray, ::NDTensors.TensorAlgebra.BlockedPermutation{1, Length, Blocks} where {Length, Blocks<:Tuple{Tuple{Vararg{Int64}}}})
   @ NDTensors ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/allocate_output.jl:23
  ...

Stacktrace:
  [1] allocate_output(::typeof(NDTensors.TensorAlgebra.contract), biperm_dest::NDTensors.TensorAlgebra.BlockedPermutation{…}, a1::Vector{…}, biperm1::NDTensors.TensorAlgebra.BlockedPermutation{…}, a2::Matrix{…}, biperm2::NDTensors.TensorAlgebra.BlockedPermutation{…}, α::Bool)
    @ NDTensors.TensorAlgebra ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/allocate_output.jl:49
  [2] contract(alg::NDTensors.BackendSelection.Algorithm{…}, biperm_dest::NDTensors.TensorAlgebra.BlockedPermutation{…}, a1::Vector{…}, biperm1::NDTensors.TensorAlgebra.BlockedPermutation{…}, a2::Matrix{…}, biperm2::NDTensors.TensorAlgebra.BlockedPermutation{…}, α::Bool; kwargs::@Kwargs{})
    @ NDTensors.TensorAlgebra ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/contract.jl:117
  [3] contract(alg::NDTensors.BackendSelection.Algorithm{…}, biperm_dest::NDTensors.TensorAlgebra.BlockedPermutation{…}, a1::Vector{…}, biperm1::NDTensors.TensorAlgebra.BlockedPermutation{…}, a2::Matrix{…}, biperm2::NDTensors.TensorAlgebra.BlockedPermutation{…}, α::Bool)
    @ NDTensors.TensorAlgebra ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/contract.jl:107
  [4] contract(alg::NDTensors.BackendSelection.Algorithm{…}, labels_dest::Tuple{…}, a1::Vector{…}, labels1::Tuple{…}, a2::Matrix{…}, labels2::Tuple{…}, α::Bool; kwargs::@Kwargs{})
    @ NDTensors.TensorAlgebra ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/contract.jl:88
  [5] contract(alg::NDTensors.BackendSelection.Algorithm{…}, labels_dest::Tuple{…}, a1::Vector{…}, labels1::Tuple{…}, a2::Matrix{…}, labels2::Tuple{…}, α::Bool)
    @ NDTensors.TensorAlgebra ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/contract.jl:77
  [6] contract(alg::NDTensors.BackendSelection.Algorithm{…}, a1::Vector{…}, labels1::Tuple{…}, a2::Matrix{…}, labels2::Tuple{…}, α::Bool; kwargs::@Kwargs{})
    @ NDTensors.TensorAlgebra ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/contract.jl:45
  [7] contract
    @ ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/contract.jl:35 [inlined]
  [8] #contract#31
    @ ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/contract.jl:32 [inlined]
  [9] contract
    @ ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/contract.jl:23 [inlined]
 [10] contract(a1::Vector{Float64}, labels1::Tuple{Int64}, a2::Matrix{Float64}, labels2::Tuple{Int64, Int64})
    @ NDTensors.TensorAlgebra ~/Documents/itensor/ITensors.jl/NDTensors/src/lib/TensorAlgebra/src/contract/contract.jl:23
 [11] top-level scope
    @ REPL[18]:1
Some type information was truncated. Use `show(err)` to see complete types.