fix(Resources): onException should be created at the top

When adding an onException to the Canvas, it's created at the end of the
YAML, but it should be created at the beginning instead.

fix: #1577

packages/ui/src/models/camel/camel-route-resource.test.ts

@@ -8,6 +8,7 @@ import { CamelComponentFilterService } from '../visualization/flows/support/came
 import { BeansEntity } from '../visualization/metadata/beansEntity';
 import { createCamelResource } from './camel-resource';
 import { CamelRouteResource } from './camel-route-resource';
+import { EntityType } from './entities';
 import { SourceSchemaType } from './source-schema-type';
 
 describe('CamelRouteResource', () => {
@@ -57,6 +58,33 @@ describe('CamelRouteResource', () => {
       expect(resource.getVisualEntities()).toHaveLength(1);
       expect(resource.getVisualEntities()[0].id).toEqual(id);
     });
+
+    it('should add new entities at the end of the list and return its ID', () => {
+      const resource = new CamelRouteResource();
+      resource.addNewEntity();
+      const id = resource.addNewEntity(EntityType.Route);
+
+      expect(resource.getVisualEntities()).toHaveLength(2);
+      expect(resource.getVisualEntities()[1].id).toEqual(id);
+    });
+
+    it('should add OnException entity at the beginning of the list and return its ID', () => {
+      const resource = new CamelRouteResource();
+      resource.addNewEntity();
+      const id = resource.addNewEntity(EntityType.OnException);
+
+      expect(resource.getVisualEntities()).toHaveLength(2);
+      expect(resource.getVisualEntities()[0].id).toEqual(id);
+    });
+
+    it('should add ErrorHandler entity at the beginning of the list and return its ID', () => {
+      const resource = new CamelRouteResource();
+      resource.addNewEntity();
+      const id = resource.addNewEntity(EntityType.ErrorHandler);
+
+      expect(resource.getVisualEntities()).toHaveLength(2);
+      expect(resource.getVisualEntities()[0].id).toEqual(id);
+    });
   });
 
   it('should return the right type', () => {

packages/ui/src/models/camel/camel-route-resource.ts

@@ -39,6 +39,7 @@ export class CamelRouteResource implements CamelResource, BeansAwareResource {
       { type: EntityType.RestConfiguration, group: 'Rest', Entity: CamelRestConfigurationVisualEntity },
     ];
   static readonly PARAMETERS_ORDER = ['id', 'description', 'uri', 'parameters', 'steps'];
+  private static readonly ERROR_RELATED_ENTITIES = [EntityType.OnException, EntityType.ErrorHandler];
   readonly sortFn = createCamelPropertiesSorter(CamelRouteResource.PARAMETERS_ORDER) as (
     a: unknown,
     b: unknown,
@@ -93,7 +94,13 @@ export class CamelRouteResource implements CamelResource, BeansAwareResource {
       const supportedEntity = CamelRouteResource.SUPPORTED_ENTITIES.find(({ type }) => type === entityType);
       if (supportedEntity) {
         const entity = new supportedEntity.Entity();
-        this.entities.push(entity);
+
+        /** Error related entities should be added at the beginning of the list */
+        if (CamelRouteResource.ERROR_RELATED_ENTITIES.includes(entityType)) {
+          this.entities.unshift(entity);
+        } else {
+          this.entities.push(entity);
+        }
         return entity.id;
       }
     }