diff --git a/python/lsst/pipe/base/pipeline_graph/visualization/_mermaid.py b/python/lsst/pipe/base/pipeline_graph/visualization/_mermaid.py
index f42ab482..db44d53e 100644
--- a/python/lsst/pipe/base/pipeline_graph/visualization/_mermaid.py
+++ b/python/lsst/pipe/base/pipeline_graph/visualization/_mermaid.py
@@ -115,18 +115,19 @@ def show_mermaid(
 
     # Render nodes.
     for node_key, node_data in xgraph.nodes.items():
-        if node_key.node_type in (NodeType.TASK, NodeType.TASK_INIT):
-            # Render a task or task-init node.
-            _render_task_node(node_key, node_data, options, stream)
-        elif node_key.node_type == NodeType.DATASET_TYPE:
-            # Render a dataset-type node with possible overflow handling.
-            overflow_ref, node_overflow_ids = _render_dataset_type_node(
-                node_key, node_data, options, stream, overflow_ref
-            )
-            if node_overflow_ids:
-                overflow_ids.extend(node_overflow_ids)
-        else:
-            raise AssertionError(f"Unexpected node type: {node_key.node_type}")
+        match node_key.node_type:
+            case NodeType.TASK | NodeType.TASK_INIT:
+                # Render a task or task-init node.
+                _render_task_node(node_key, node_data, options, stream)
+            case NodeType.DATASET_TYPE:
+                # Render a dataset-type node with possible overflow handling.
+                overflow_ref, node_overflow_ids = _render_dataset_type_node(
+                    node_key, node_data, options, stream, overflow_ref
+                )
+                if node_overflow_ids:
+                    overflow_ids += node_overflow_ids
+            case _:
+                raise AssertionError(f"Unexpected node type: {node_key.node_type}")
 
     # Collect edges for printing and track which ones are prerequisite
     # so we can apply dashed styling after printing them.