Stack on an empty collection for iterative svd

[Confusio]

https://github.com/QuantumKitHub/PEPSKit.jl/blob/994a94f8d0069490aac9b106d56dadfd587e50a8/src/utility/svd.jl#L265C1-L284

When the truncation space has less sector than the domain of the TensorMap f, there is an error
'''
ERROR: LoadError: ArgumentError: stack on an empty collection is not allowed
'''