fix(core): Prevent workflow history saving error from happening (#7812)

When performing actions such as renaming a workflow or updating its
settings, n8n errors with "Failed to save workflow version" in the
console although the saving process was successful. We are now correctly
checking whether `nodes` and `connections` exist and only then save a
snapshot.

Github issue / Community forum post (link here to close automatically):

packages/cli/src/workflows/workflowHistory/workflowHistory.service.ee.ts

@@ -66,7 +66,10 @@ export class WorkflowHistoryService {
 	}
 
 	async saveVersion(user: User, workflow: WorkflowEntity, workflowId: string) {
-		if (isWorkflowHistoryEnabled()) {
+		// On some update scenarios, `nodes` and `connections` are missing, such as when
+		// changing workflow settings or renaming. In these cases, we don't want to save
+		// a new version
+		if (isWorkflowHistoryEnabled() && workflow.nodes && workflow.connections) {
 			try {
 				await this.workflowHistoryRepository.insert({
 					authors: user.firstName + ' ' + user.lastName,