fix with empty tensors

Author: lkdvos

src/auxiliary/blockarrays.jl

@@ -1,4 +1,3 @@
-copy_dense(A) = copy_dense!(similar(first(A.blocks), size(A)), A)
 function copy_dense!(Adense, A)
     for block_index in Iterators.product(blockaxes(A)...)
         a = view(A, block_index...)

src/linalg/factorizations.jl

@@ -25,7 +25,7 @@ for f! in (
     )
     @eval function MAK.$f!(t::AbstractBlockTensorMap, F, alg::AbstractAlgorithm)
         TensorKit.foreachblock(t, F...) do _, (tblock, Fblocks...)
-            Fblocks′ = MAK.$f!(copy_dense(tblock), alg)
+            Fblocks′ = MAK.$f!(copy_dense!(similar(tblock, size(tblock)), tblock), alg)
             # deal with the case where the output is not in-place
             for (b′, b) in zip(Fblocks′, Fblocks)
                 b === b′ || copy!(b, b′)
@@ -44,7 +44,7 @@ for f! in (
     )
     @eval function MAK.$f!(t::AbstractBlockTensorMap, N, alg::AbstractAlgorithm)
         TensorKit.foreachblock(t, N) do _, (tblock, Nblock)
-            Nblock′ = MAK.$f!(copy_dense(tblock), alg)
+            Nblock′ = MAK.$f!(copy_dense!(similar(tblock, size(tblock)), tblock), alg)
             # deal with the case where the output is not the same as the input
             Nblock === Nblock′ || copy!(Nblock, Nblock′)
             return nothing