improve Tangle logic for unknown root msg

lib/feed-v1/tangle.js

@@ -85,13 +85,16 @@ class Tangle {
   }
 
   add(msgHash, msg) {
-    const tangles = msg.metadata.tangles
-    if (msgHash === this.#rootHash) {
+    if (msgHash === this.#rootHash && !this.#rootMsg) {
       this.#tips.add(msgHash)
       this.#perDepth.set(0, [msgHash])
       this.#depth.set(msgHash, 0)
       this.#rootMsg = msg
-    } else if (tangles[this.#rootHash]) {
+      return
+    }
+
+    const tangles = msg.metadata.tangles
+    if (msgHash !== this.#rootHash && tangles[this.#rootHash]) {
       this.#tips.add(msgHash)
       const prev = tangles[this.#rootHash].prev
       for (const p of prev) {
@@ -105,6 +108,7 @@ class Tangle {
       atDepth.push(msgHash)
       atDepth.sort(compareMsgHashes)
       this.#perDepth.set(depth, atDepth)
+      return
     }
   }
 
@@ -120,6 +124,10 @@ class Tangle {
    * @returns {Array<string>}
    */
   topoSort() {
+    if (!this.#rootMsg) {
+      console.warn('Tangle is missing root message')
+      return []
+    }
     const sorted = []
     const max = this.#maxDepth
     for (let i = 0; i <= max; i++) {
@@ -136,6 +144,10 @@ class Tangle {
    * @returns {Set<string>}
    */
   getTips() {
+    if (!this.#rootMsg) {
+      console.warn('Tangle is missing root message')
+      return new Set()
+    }
     return this.#tips
   }
 
@@ -144,6 +156,10 @@ class Tangle {
    * @returns {Set<string>}
    */
   getLipmaaSet(depth) {
+    if (!this.#rootMsg) {
+      console.warn('Tangle is missing root message')
+      return new Set()
+    }
     const lipmaaDepth = lipmaa(depth + 1) - 1
     return new Set(this.#getAllAtDepth(lipmaaDepth))
   }
@@ -165,6 +181,10 @@ class Tangle {
   }
 
   isFeed() {
+    if (!this.#rootMsg) {
+      console.warn('Tangle is missing root message')
+      return false
+    }
     if (this.#rootMsg.content) return false
     const metadata = this.#rootMsg.metadata
     return metadata.size === 0 && metadata.hash === null
@@ -177,6 +197,10 @@ class Tangle {
   }
 
   shortestPathToRoot(msgHash) {
+    if (!this.#rootMsg) {
+      console.warn('Tangle is missing root message')
+      return []
+    }
     const path = []
     let current = msgHash
     while (true) {