Fix epsilon derivatives (#5)

Fixes inverter_noise test in Cedar.

src/transform/state_reconstruct/derivative.jl

@@ -86,7 +86,7 @@ The `vars` that are being reconstructed must appear in sorted order.
         T == AbstractVector{<:Number} ? Vector{Float64} :
         T
     end...}
-    F! = JITOpaqueClosure{:reconstruct_derivative, goldclass_sig}() do arg_types...
+    F! = JITOpaqueClosure{with_eps ? :reconstruct_derivative_with_eps : :reconstruct_derivative, goldclass_sig}() do arg_types...
         ir = copy(ir)
         ir.argtypes[2:end] .= arg_types
 
@@ -192,9 +192,9 @@ function define_transform_for_reconstruct_der(var_assignment, vars, obs, param_b
             @assert with_eps
             eps_ii = epsnum(inst[:type])
             input_basis_row = ntuple(neqs + nparams + neps) do active_state_ii
-                Float64(var_ii == (active_state_ii - neqs + nparams))
+                Float64(eps_ii == (active_state_ii - neqs + nparams))
             end
-            replace_call!(ir, ssa, Expr(:call, BatchOfBundles{neqs + nparams + neps}, u_ii, input_basis_row...))
+            replace_call!(ir, ssa, Expr(:call, BatchOfBundles{neqs + nparams + neps}, 0., input_basis_row...))
             return nothing
         elseif is_solved_variable(stmt) || is_known_invoke(stmt, observed!, ir)
             if is_solved_variable(stmt)
@@ -248,7 +248,7 @@ function get_reconstruct_der_visit_custom!(var_assignment)
         end
 
         stmt = ir[ssa][:inst]
-        if is_known_invoke_or_call(stmt, variable, ir) || is_known_invoke_or_call(stmt, state_ddt, ir)
+        if is_known_invoke_or_call(stmt, variable, ir) || is_known_invoke_or_call(stmt, state_ddt, ir) || is_known_invoke(stmt, epsilon, ir)
             return true
         elseif is_known_invoke_or_call(stmt, solved_variable, ir)
             recurse(stmt.args[end])