sqldb+graph/db: fix UpsertNode bug

Account for the last_update field being null.

sqldb/sqlc/graph.sql.go

@@ -542,7 +542,8 @@ ON CONFLICT (pub_key, version)
         last_update = EXCLUDED.last_update,
         color = EXCLUDED.color,
         signature = EXCLUDED.signature
-WHERE EXCLUDED.last_update > nodes.last_update
+WHERE nodes.last_update IS NULL
+    OR EXCLUDED.last_update > nodes.last_update
 RETURNING id
 `
 

sqldb/sqlc/queries/graph.sql

@@ -17,7 +17,8 @@ ON CONFLICT (pub_key, version)
         last_update = EXCLUDED.last_update,
         color = EXCLUDED.color,
         signature = EXCLUDED.signature
-WHERE EXCLUDED.last_update > nodes.last_update
+WHERE nodes.last_update IS NULL
+    OR EXCLUDED.last_update > nodes.last_update
 RETURNING id;
 
 -- name: GetNodeByPubKey :one