fix: incorrect tuple indexing

Author: avik-pal

src/solutions/solution_interface.jl

@@ -4,7 +4,7 @@ const AllObserved = RecursiveArrayTools.AllObserved
 # No Time Solution : Forward to `A.u`
 Base.getindex(A::AbstractNoTimeSolution) = A.u[]
 Base.getindex(A::AbstractNoTimeSolution, i::Int) = A.u[i]
-Base.getindex(A::AbstractNoTimeSolution, I::Vararg{Int, N}) where {N} = A.u[I]
+Base.getindex(A::AbstractNoTimeSolution, I::Vararg{Int, N}) where {N} = A.u[I...]
 Base.getindex(A::AbstractNoTimeSolution, I::AbstractArray{Int}) = A.u[I]
 Base.getindex(A::AbstractNoTimeSolution, I::CartesianIndex) = A.u[I]
 Base.getindex(A::AbstractNoTimeSolution, I::Colon) = A.u[I]