message: Drop session if release is not a string or is missing and log
diff: @@ -152,8 +152,8 @@ export abstract class BaseClient<B extends Backend, O extends Options> implement
  * @inheritDoc
  */
  public captureSession(session: Session): void {
  - if (!session.release) {
  - logger.warn('Discarded session because of missing release');
  + if (!(typeof session.release === 'string')) {
  + logger.warn('Discarded session because of missing or non-string release');
  } else {
  this._sendSession(session);
  // After sending, we set init false to inidcate it's not the first occurence
  