fix type stability

Author: lkdvos

ext/MatrixAlgebraKitChainRulesCoreExt.jl

@@ -43,8 +43,7 @@ for qr_f in (:qr_compact, :qr_full)
 end
 function ChainRulesCore.rrule(::typeof(qr_null!), A::AbstractMatrix, N, alg)
     Ac = copy_input(qr_full, A)
-    QR = initialize_output(qr_full!, A, alg)
-    QR = qr_full!(Ac, QR, alg)
+    QR = qr_full!(Ac, initialize_output(qr_full!, A, alg), alg)
     N = copy!(N, view(QR[1], 1:size(A, 1), (size(A, 2) + 1):size(A, 1)))
     function qr_null_pullback(ΔN)
         ΔA = zero(A)
@@ -77,8 +76,7 @@ for lq_f in (:lq_compact, :lq_full)
 end
 function ChainRulesCore.rrule(::typeof(lq_null!), A::AbstractMatrix, Nᴴ, alg)
     Ac = copy_input(lq_full, A)
-    LQ = initialize_output(lq_full!, A, alg)
-    LQ = lq_full!(Ac, LQ, alg)
+    LQ = lq_full!(Ac, initialize_output(lq_full!, A, alg), alg)
     Nᴴ = copy!(Nᴴ, view(LQ[2], (size(A, 1) + 1):size(A, 2), 1:size(A, 2)))
     function lq_null_pullback(ΔNᴴ)
         ΔA = zero(A)