message: fix(lib): Fix MIME type exclusion condition
  As `mime.extension()` returns `false`, instead of `null` or `undefined`,
  this condition simply needs to check for truthyness.
  Change-type: patch
diff: @@ -40,7 +40,7 @@ exports.getCompressedExtensions = () => {
  for (const [ mimetype, cls ] of sdk.sourceDestination.SourceDestination.mimetypes.entries()) {
  if (cls.prototype instanceof sdk.sourceDestination.CompressedSource) {
  const extension = mime.extension(mimetype)
  - if (extension !== null) {
  + if (extension) {
  result.push(extension)
  }
  }
  