[Eager] [Bug Fix] fix eager trace op bug (#40402)

* fix some slice bug, test=develop

* refine, test=develop

python/paddle/fluid/dygraph/tracer.py

@@ -140,7 +140,12 @@ class Tracer(core.Tracer):
                             outputs[retname][j].reconstruct_from_(returns[i][j],
                                                                   False)
                     else:
-                        outputs[retname][0].reconstruct_from_(returns[i], False)
+                        if isinstance(outputs[retname], list):
+                            outputs[retname][0].reconstruct_from_(returns[i],
+                                                                  False)
+                        else:
+                            outputs[retname].reconstruct_from_(returns[i],
+                                                               False)
         elif isinstance(returns, list):
             assert len(outputs.keys()) == 1
             key = list(outputs.keys())[0]