better fallbacks

Author: ChrisRackauckas

ext/LinearSolveSparseArraysExt.jl

@@ -71,6 +71,14 @@ end
 const PREALLOCATED_UMFPACK = SparseArrays.UMFPACK.UmfpackLU(SparseMatrixCSC(0, 0, [1],
     Int[], Float64[]))
 
+function LinearSolve.init_cacheval(
+        alg::Union{LUFactorization, GenericLUFactorization}, A::AbstractSparseArray{<:Number, <:Integer}, b, u,
+        Pl, Pr,
+        maxiters::Int, abstol, reltol,
+        verbose::Bool, assumptions::OperatorAssumptions)
+    nothing
+end
+
 function LinearSolve.init_cacheval(
         alg::UMFPACKFactorization, A::AbstractArray, b, u,
         Pl, Pr,