Improve recursive type error (#1028)

* Improve recursive type error

* Update src/Tracing.jl

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: wsmoses

src/Tracing.jl

@@ -1115,6 +1115,13 @@ function make_tracer_unknown(
             if xi !== xi2
                 changed = true
             end
+            if mode != TracedToTypes && !(Core.Typeof(xi2) <: fieldtype(TT, i))
+                throw(
+                    AssertionError(
+                        "Could not recursively make tracer of object of type $RT into $TT at field $i (named $(fieldname(TT, i))), need object of type $(fieldtype(TT, i)) found object of type $(Core.Typeof(xi2)) ",
+                    ),
+                )
+            end
             flds[i] = xi2
         else
             nf = i - 1 # rest of tail must be undefined values