Throw when creating tx (simplify)

index.js

@@ -108,7 +108,6 @@ class HypercoreStorage {
   }
 
   atomize (atom) {
-    if (this.snapshotted) throw new Error('Cannot atomize a snapshot')
     if (this.atom && this.atom !== atom) throw new Error('Cannot atomize and atomized session with a new atom')
     return new HypercoreStorage(this.store, this.db.session(), this.core, atom.view, atom)
   }
@@ -164,7 +163,6 @@ class HypercoreStorage {
   }
 
   async createSession (name, head) {
-    if (this.snapshotted) throw new Error('Cannot create session on snapshot')
     const rx = this.read()
 
     const existingSessionsPromise = rx.getSessions()
@@ -250,7 +248,6 @@ class HypercoreStorage {
   }
 
   write () {
-    if (this.snapshotted) throw new Error('Cannot write to snapshot')
     return new CoreTX(this.core, this.db, this.atom ? this.view : null, [])
   }
 

lib/tx.js

@@ -16,6 +16,7 @@ const CORE_HINTS = schema.getEncoding('@core/hints')
 
 class CoreTX {
   constructor (core, db, view, changes) {
+    if (db.snapshotted) throw new Error('Cannot open core tx on snapshot')
     this.core = core
     this.db = db
     this.view = view

test/core.js

@@ -637,7 +637,7 @@ test('cannot open tx on snapshot', async (t) => {
   const snap = core.snapshot()
   t.exception(
     () => snap.write(),
-    /Cannot write to snapshot/
+    /Cannot open core tx on snapshot/
   )
 })
 
@@ -647,16 +647,6 @@ test('cannot create sessions on snapshot', async (t) => {
 
   await t.exception(
     async () => await snap.createSession(),
-    /Cannot create session on snapshot/
-  )
-})
-
-test('cannot atomize snapshot', async (t) => {
-  const core = await createCore(t)
-  const snap = core.snapshot()
-
-  await t.exception(
-    async () => snap.atomize(snap.createAtom()),
-    /Cannot atomize a snapshot/
+    /Cannot open core tx on snapshot/
   )
 })