filterByTag check never throws due to List() truthyness

[adhooaa]

At message.js:158 there is:
const symESKeyPacketlist = this.packets.filterByTag(enums.packet.symEncryptedSessionKey); if (!symESKeyPacketlist) { throw new Error('No symmetrically encrypted session key packet found.'); }
However the implementation filterByTag always returns a new List() (which may be empty).

Even when empty, if (!symESKeyPacketlist) { always evaluates false because empty lists are still truthy

There may be other places in the code that follows this pattern...

[twiss]

Thanks, good catch! In this case, it shouldn't matter too much if that list is empty as we'd still throw a bit further down:

openpgpjs/src/message.js

Line 240 in 43441bf

throw exception || new Error('Session key decryption failed.');

However, feel free to make a PR anyway, in order to improve the error message, and to fix any other cases if you find them.