tons of fixes

src/App.vue

@@ -62,6 +62,8 @@ function onConnect(connection: Connection) {
 }
 
 function run() {
+  if (nodes.value.length === 0) { alert('Add at least one node first.'); return }
+  if (edges.value.length === 0) { alert('Connect the nodes with at least one wire first.'); return }
   const graph = buildGraph(nodes.value, edges.value)
   studio.send({ type: 'load_graph', graph })
 }