Return null instead of throwing on property errs (#8)

Trying to fix https://codeberg.org/pzp/pzp-sync/issues/10

This doesn't solve the problem of missing rootMsg but maybe allows sync to fail more gracefully

Reviewed-on: https://codeberg.org/pzp/pzp-db/pulls/8
Co-authored-by: Jacob Karlsson <jacob.karlsson95@gmail.com>
Co-committed-by: Jacob Karlsson <jacob.karlsson95@gmail.com>

lib/index.js

@@ -131,7 +131,7 @@ class DBTangle extends MsgV4.Tangle {
    * *Erasables* are msgs that precede `msgsIDs` and can be erased without
    * losing a validation path toward the root.
    * @param {Array<MsgID>} msgIDs
-   * @returns {{ deletables: Set<MsgID>, erasables: Set<MsgID> }}
+   * @returns {{ deletables: Set<MsgID>, erasables: Set<MsgID> } | null}
    */
   getDeletablesAndErasables(...msgIDs) {
     // Determine erasables
@@ -139,6 +139,7 @@ class DBTangle extends MsgV4.Tangle {
     const minimum = this.getMinimumAmong(msgIDs)
     for (const msgID of minimum) {
       const trail = this.shortestPathToRoot(msgID)
+      if (!trail) return null
       for (const id of trail) {
         erasables.add(id)
       }
@@ -174,6 +175,7 @@ class DBTangle extends MsgV4.Tangle {
     const trail = new Set()
     for (const msgID of minSetTight) {
       const path = this.shortestPathToRoot(msgID)
+      if (!path) return cb(Error("Couldn't get shortest path to root when slicing dbtangle"))
       for (const msgID of path) {
         trail.add(msgID)
       }
@@ -529,16 +531,17 @@ function initDB(peer, config) {
           rec.msg.metadata.accountTips,
           (err, sigkeys) => {
             if (err) return cb(err)
-
+            // TODO: how is sigkeys able to be undefined here? typechecker why are you weird?
+            if (!sigkeys) return cb(Error("Sigkeys missing somehow"))
             // Don't accept ghosts to come back, unless they are trail msgs
             if (!!rec.msg.data && ghosts.read(tangleID).has(rec.id)) {
               return cb(Error('Refusing a ghost msg to come back'))
             }
 
-            if (
-              (err = MsgV4.validate(rec.msg, tangle, sigkeys, rec.id, tangleID))
-            ) {
-              return cb(Error('Invalid msg', { cause: err }))
+            
+            const valErr = MsgV4.validate(rec.msg, tangle, sigkeys, rec.id, tangleID)
+            if (valErr) {
+              return cb(Error('Invalid msg', { cause: valErr }))
             }
 
             /** @param {CB<void>} cb */

lib/msg-v4/tangle.js

@@ -222,11 +222,12 @@ class Tangle {
   }
 
   /**
-   * @returns {'feed' | 'account' | 'weave'}
+   * @returns {'feed' | 'account' | 'weave' | null}
    */
   get type() {
     if (!this.#rootMsg) {
-      throw new Error(`Tangle "${this.#rootID}" is missing root message`)
+      console.trace(new Error(`Tangle "${this.#rootID}" is missing root message`))
+      return null
     }
     if (this.#isFeed()) return 'feed'
     if (this.#rootMsg.metadata.account === 'self') return 'account'
@@ -235,7 +236,8 @@ class Tangle {
 
   get root() {
     if (!this.#rootMsg) {
-      throw new Error(`Tangle "${this.#rootID}" is missing root message`)
+      console.trace(new Error(`Tangle "${this.#rootID}" is missing root message`))
+      return null
     }
     return this.#rootMsg
   }
@@ -256,7 +258,8 @@ class Tangle {
       if (!prev) break
       if (prev === lastPrev) {
         // prettier-ignore
-        throw new Error(`Tangle "${this.#rootID}" has a cycle or lacking a trail to root`)
+        console.trace(new Error(`Tangle "${this.#rootID}" has a cycle or lacking a trail to root`))
+        return null
       } else {
         lastPrev = prev
       }

lib/msg-v4/validation.js

@@ -107,6 +107,8 @@ function validateSigkeyAndAccount(msg, tangle, sigkeys) {
       // prettier-ignore
       return `invalid msg: accountTips "${msg.metadata.accountTips}" should have been null in an account tangle\n` + JSON.stringify(msg)
     }
+  } else if (tangle.type === null) {
+    return "Cannot validate tangle of unknown type"
   }
   return undefined
 }
@@ -199,6 +201,8 @@ function validateTangle(msg, tangle, tangleID) {
       // prettier-ignore
       return `invalid msg: account "${msg.metadata.account}" should have been feed account "${account}"\n` + JSON.stringify(msg)
     }
+  } else if (tangle.type === null) {
+    return "Unknown tangle type"
   }
   let lastPrev = null
   let minDiff = Infinity
@@ -342,11 +346,8 @@ function validate(msg, tangle, sigkeys, msgID, rootID) {
   if ((err = validateSigkey(msg))) return err
   if ((err = validateData(msg))) return err
 
-  try {
-    if (tangle.type === 'feed' && isMoot(msg)) return // nothing else to check
-  } catch (/** @type {any} */ err) {
-    return err
-  }
+  if (tangle.type === 'feed' && isMoot(msg)) return // nothing else to check
+  if (tangle.type === null) return "Missing tangle type when validating msg"
 
   if ((err = validateDataSizeHash(msg))) return err
   if ((err = validateDomain(msg.metadata.domain))) return err
@@ -357,6 +358,7 @@ function validate(msg, tangle, sigkeys, msgID, rootID) {
     if ((err = validateTangle(msg, tangle, rootID))) return err
   }
   if ((err = validateSignature(msg))) return err
+  return undefined
 }
 
 module.exports = {