fix(core): Fix pairedItem issue with partial manual executions (#8575)

Co-authored-by: Danny Martini <danny@n8n.io>
Co-authored-by: कारतोफ्फेलस्क्रिप्ट™ <aditya@netroy.in>

cypress/e2e/19-execution.cy.ts

@@ -569,4 +569,27 @@ describe('Execution', () => {
 			expect(interception.request.body.runData).to.include.all.keys(expectedRunDataKeys);
 		});
 	});
+
+	it('should successfully execute partial executions with nodes attached to the second output', () => {
+		cy.createFixtureWorkflow(
+			'Test_Workflow_pairedItem_incomplete_manual_bug.json',
+			'My test workflow',
+		);
+
+		cy.intercept('POST', '/rest/workflows/run').as('workflowRun');
+
+		workflowPage.getters.zoomToFitButton().click();
+		workflowPage.getters.executeWorkflowButton().click();
+		workflowPage.getters
+			.canvasNodeByName('Test Expression')
+			.findChildByTestId('execute-node-button')
+			.click({ force: true });
+
+		// Check  toast (works because Cypress waits enough for the element to show after the http request node has finished)
+		// Wait for the execution to return.
+		cy.wait('@workflowRun');
+		// Wait again for the websocket message to arrive and the UI to update.
+		cy.wait(100);
+		workflowPage.getters.errorToast({ timeout: 1 }).should('not.exist');
+	});
 });