Issue a single structure exactly at bounds warning

tidy3d/components/base_sim/simulation.py

@@ -150,6 +150,7 @@ def _structures_not_at_edges(cls, val, values):
                             "use td.inf as a size variable instead to make this explicit.",
                             custom_loc=["structures", istruct],
                         )
+                        continue
 
         return val