Add some checks for qgraph metadata

python/lsst/pipe/base/quantum_provenance_graph.py

@@ -980,14 +980,19 @@ def assemble_quantum_provenance_graph(
         curse_failed_logs: bool = False,
     ) -> None:
         output_runs = []
-        for count, qgraph in enumerate(qgraphs):
-            if not isinstance(qgraph, QuantumGraph):
-                qgraph = QuantumGraph.loadUri(qgraph)
+        for count, graph in enumerate(qgraphs):
+            qgraph = graph if isinstance(graph, QuantumGraph) else QuantumGraph.loadUri(graph)
+            assert qgraph.metadata is not None, "Saved QGs always have metadata."
             # If the most recent graph's timestamp was earlier than any of the
             # previous graphs, raise a RuntimeError.
             if len(qgraphs) > 1:
-                for graph in qgraphs[: count - 1]:
-                    if qgraph.metadata["time"] < graph.metadata["time"]:
+                for previous_graph in qgraphs[: count - 1]:
+                    previous_graph = (
+                        previous_graph
+                        if isinstance(previous_graph, QuantumGraph)
+                        else QuantumGraph.loadUri(previous_graph)
+                    )
+                    if qgraph.metadata["time"] < previous_graph.metadata["time"]:
                         raise RuntimeError(
                             """add_new_graph may only be called on graphs
                             which are passed in the order they were