beam: fix mixed-type node crash in toposort ready-queue sort

wizard-work/beam/toposort/toposort.py

@@ -50,14 +50,14 @@ def topo_sort(graph: Mapping[Any, Iterable[Any]]) -> TopoResult:
 
     # ready set as a min-heap via sorted list (nodes sortable; if not, fall back)
     try:
-        ready = sorted(n for n in nodes if in_deg[n] == 0)
+        ready = sorted((n for n in nodes if in_deg[n] == 0), key=_key)
     except TypeError:
         ready = [n for n in nodes if in_deg[n] == 0]
     out: list[Any] = []
     # We'll use a list as a priority queue by re-sorting on pop; fine for tests.
     while ready:
         # pop smallest
-        ready.sort()
+        ready.sort(key=_key)
         cur = ready.pop(0)
         out.append(cur)
         for dep in sorted(dependents[cur], key=_key):
@@ -171,6 +171,6 @@ def topo_sort(graph: Mapping[Any, Iterable[Any]]) -> TopoResult:
 
 def _key(x):
     try:
-        return (0, x)
+        return (0, type(x).__name__, x)
     except TypeError:
         return (1, id(x))