fix: fix bug in remake_buffer

Author: AayushSabharwal

src/systems/parameter_buffer.jl

@@ -397,7 +397,8 @@ function SymbolicIndexingInterface.remake_buffer(sys, oldbuf::MTKParameters, val
     @set! newbuf.nonnumeric = narrow_buffer_type_and_fallback_undefs.(
         oldbuf.nonnumeric, newbuf.nonnumeric)
     if newbuf.dependent_update_oop !== nothing
-        @set! newbuf.dependent = newbuf.dependent_update_oop(newbuf...)
+        @set! newbuf.dependent = split_into_buffers(
+            newbuf.dependent_update_oop(newbuf...), oldbuf.dependent)
     end
     return newbuf
 end
@@ -421,6 +422,7 @@ _num_subarrays(v::Tuple) = length(v)
 # getindex indexes the vectors, setindex! linearly indexes values
 # it's inconsistent, but we need it to be this way
 function Base.getindex(buf::MTKParameters, i)
+    i_orig = i
     if !isempty(buf.tunable)
         i <= _num_subarrays(buf.tunable) && return _subarrays(buf.tunable)[i]
         i -= _num_subarrays(buf.tunable)
@@ -441,7 +443,7 @@ function Base.getindex(buf::MTKParameters, i)
         i <= _num_subarrays(buf.dependent) && return _subarrays(buf.dependent)[i]
         i -= _num_subarrays(buf.dependent)
     end
-    throw(BoundsError(buf, i))
+    throw(BoundsError(buf, i_orig))
 end
 function Base.setindex!(p::MTKParameters, val, i)
     function _helper(buf)
@@ -525,9 +527,6 @@ function jacobian_wrt_vars(pf::F, p::MTKParameters, input_idxs, chunk::C) where
             for (i, val) in zip(input_idxs, p_small_inner)
                 _set_parameter_unchecked!(p_big, val, i)
             end
-            # tunable, repack, _ = SciMLStructures.canonicalize(SciMLStructures.Tunable(), p_big)
-            # tunable[input_idxs] .= p_small_inner
-            # p_big = repack(tunable)
             return if pf isa SciMLBase.ParamJacobianWrapper
                 buffer = Array{dualtype}(undef, size(pf.u))
                 pf(buffer, p_big)
@@ -537,8 +536,6 @@ function jacobian_wrt_vars(pf::F, p::MTKParameters, input_idxs, chunk::C) where
             end
         end
     end
-    # tunable, _, _ = SciMLStructures.canonicalize(SciMLStructures.Tunable(), p)
-    # p_small = tunable[input_idxs]
     p_small = parameter_values.((p,), input_idxs)
     cfg = ForwardDiff.JacobianConfig(p_closure, p_small, chunk, tag)
     ForwardDiff.jacobian(p_closure, p_small, cfg, Val(false))