fix(backend): make value of flow_version not null (#4039)

* fix: flow versioning nit: make value of flow version not null

* fix: sqlx

* fix: missing code change

* fix: improve nit migration

backend/.sqlx/query-4a764cdcb847b71183425a7a0e863708ef7fe2c88b28d0667988a47b9e995c0e.json

@@ -16,7 +16,7 @@
       ]
     },
     "nullable": [
-      true
+      false
     ]
   },
   "hash": "4a764cdcb847b71183425a7a0e863708ef7fe2c88b28d0667988a47b9e995c0e"

backend/migrations/20240708075901_flow_versioning_nit.down.sql

@@ -0,0 +1,2 @@
+-- Add down migration script here
+ALTER TABLE flow_version ALTER COLUMN value DROP NOT NULL;

backend/migrations/20240708075901_flow_versioning_nit.up.sql

@@ -0,0 +1,3 @@
+-- Add up migration script here
+UPDATE flow_version SET value = '{"modules":[]}'::jsonb WHERE value IS NULL;
+ALTER TABLE flow_version ALTER COLUMN value SET NOT NULL;

backend/windmill-worker/src/dedicated_worker.rs

@@ -415,7 +415,7 @@ pub async fn create_dedicated_worker_map(
                 flow_path,
                 _wp.workspace_id
             )
-            .fetch_one(db)
+            .fetch_optional(db)
             .await;
             if let Ok(v) = value {
                 if let Some(v) = v {