fix: handle DDEs in GeneratedFunctionWrapper call in build_explicit_observed_function

Author: AayushSabharwal

src/systems/diffeqs/odesystem.jl

@@ -527,12 +527,14 @@ function build_explicit_observed_function(sys, ts;
     if fns isa Tuple
         oop, iip = eval_or_rgf.(fns; eval_expression, eval_module)
         f = GeneratedFunctionWrapper{(
-            p_start, length(args) - length(ps) + 1, is_split(sys))}(oop, iip)
+            p_start + is_dde(sys), length(args) - length(ps) + 1 + is_dde(sys), is_split(sys))}(
+            oop, iip)
         return return_inplace ? (f, f) : f
     else
         f = eval_or_rgf(fns; eval_expression, eval_module)
         f = GeneratedFunctionWrapper{(
-            p_start, length(args) - length(ps) + 1, is_split(sys))}(f, nothing)
+            p_start + is_dde(sys), length(args) - length(ps) + 1 + is_dde(sys), is_split(sys))}(
+            f, nothing)
         return f
     end
 end