I get error Operator '+' cannot be applied to types 'Buffer'

when i tried to add Buffer data using + operator in node js with ts !!

Code is something like:

let  encrypted = Buffer.concat([iv, ciphertext, cipher.final()]).toString('base64');

or

let plaintext = Buffer.concat([decipher.update(ciphertext), decipher.final()], 2);

About Buffer Method

(method) Buffer.concat(list: readonly Uint8Array[], totalLength?: number): Buffer

It Returns a buffer which is the result of concatenating all the buffers in the list together.