fix(core): fix single-node execution failing in main mode (#4421)

* 🐛 Fix Manual Trigger group

* 🐛 Account for single-node execution

packages/nodes-base/nodes/ManualTrigger/ManualTrigger.node.ts

@@ -6,7 +6,7 @@ export class ManualTrigger implements INodeType {
 		displayName: 'Manual Trigger',
 		name: 'manualTrigger',
 		icon: 'fa:mouse-pointer',
-		group: ['trigger', 'input'],
+		group: ['trigger'],
 		version: 1,
 		description: 'Runs the flow on clicking a button in n8n',
 		maxNodes: 1,

packages/workflow/src/Workflow.ts

@@ -899,6 +899,10 @@ export class Workflow {
 		for (const nodeName of nodeNames) {
 			node = this.nodes[nodeName];
 
+			if (nodeNames.length === 1 && !node.disabled) {
+				return node;
+			}
+
 			nodeType = this.nodeTypes.getByNameAndVersion(node.type, node.typeVersion) as INodeType;
 
 			if (nodeType && (nodeType.trigger !== undefined || nodeType.poll !== undefined)) {