Fix get_unknowns for GeneralStressState with no unknowns

Author: KnutAM

src/stressiterations.jl

@@ -422,14 +422,14 @@ function get_unknowns(state::GeneralStressState{Nσ}, a::AbstractTensor{2,3,T})
     shear_factor = a isa SymmetricTensor ? T(√2) : one(T)
     s(i,j) = i==j ? one(T) : shear_factor
     f(c) = ((i,j) = c; s(i,j)*(a[i,j]-state.σ[i,j]))
-    return SVector{Nσ}((f(c) for c in state.σm_inds))
+    return SVector{Nσ,T}((f(c) for c in state.σm_inds))
 end
 
 function get_unknowns(state::GeneralStressState{Nσ}, a::AbstractTensor{4,3,T}) where {Nσ,T}
     shear_factor = T(√2)
     s(i,j) = i==j ? one(T) : shear_factor
     f(c1,c2) = ((i,j) = c1; (k,l) = c2; a[i,j,k,l]*s(i,j)*s(k,l))
-    return SMatrix{Nσ,Nσ}((f(c1,c2) for c1 in state.σm_inds, c2 in state.σm_inds))
+    return SMatrix{Nσ,Nσ,T}((f(c1,c2) for c1 in state.σm_inds, c2 in state.σm_inds))
 end
 
 # Extract each part of the stiffness tensor as SMatrix