Prevent duplicate nodes from being added to a `PublicationTree`

Suggestion from https://gitworkshop.dev/silberengel@gitcitadel.com/Alexandria/prs/note1jygtyvjnrd2yz674mqq5emd0pl69ezv2u6nhvr7f0zhcdnshlnqskf94df

deno.lock

@@ -3201,8 +3201,10 @@
         "npm:@types/d3@^7.4.3",
         "npm:@types/he@1.2",
         "npm:@types/node@22",
+        "npm:@types/qrcode@^1.5.5",
         "npm:asciidoctor@3.0",
         "npm:autoprefixer@10",
+        "npm:bech32@2",
         "npm:d3@^7.9.0",
         "npm:eslint-plugin-svelte@2",
         "npm:flowbite-svelte-icons@2.1",
@@ -3217,6 +3219,7 @@
         "npm:postcss@8",
         "npm:prettier-plugin-svelte@3",
         "npm:prettier@3",
+        "npm:qrcode@^1.5.4",
         "npm:svelte-check@4",
         "npm:svelte@5",
         "npm:tailwind-merge@^3.3.0",

src/lib/data_structures/publication_tree.ts

@@ -464,6 +464,11 @@ export class PublicationTree implements AsyncIterable<NDKEvent | null> {
   }
 
   #addNode(address: string, parentNode: PublicationTreeNode) {
+    if (this.#nodes.has(address)) {
+      console.debug(`[PublicationTree] Node with address ${address} already exists.`);
+      return;
+    }
+
     const lazyNode = new Lazy<PublicationTreeNode>(() => this.#resolveNode(address, parentNode));
     parentNode.children!.push(lazyNode);
     this.#nodes.set(address, lazyNode);