matrix-js-sdk's LocalStorageCryptoStore.getEndToEndSessionsBatch()
returns olm sessions without the deviceKey/sessionId fields, since
those live only in the storage key path. initRustCrypto()'s migration
then assigns the undefined deviceKey to PickledSession.senderKey and
crashes in the WASM setter with "Cannot read properties of undefined
(reading 'length')". The IndexedDB backend embeds those fields in the
record and is unaffected, which is why this only hit installs that
were started on the legacy localStorage crypto store.
Patch the instance to re-derive deviceKey/sessionId from the
crypto.sessions/<deviceKey> keys before returning a batch, so both
the migration and its delete-after-migrate step work.
skylord123
bc97c564d3