Why so many possibly undefined fields in Assets?

[lclarkg18]

I'm using typescript and I have ended up with code looking like this:

    await launchCamera({mediaType: 'mixed', saveToPhotos: true}).then(
      async imageResponse => {
        if (
          imageResponse.assets &&
          imageResponse.assets[0].uri &&
          imageResponse.assets[0].fileName &&
          imageResponse.assets[0].type
        ) {
          await uploadDocument(
            {
              uri: imageResponse.assets[0].uri.replace('file://', ''),
              name: imageResponse.assets[0].fileName,
              type: imageResponse.assets[0].type,
            },
          )
         ---

I understand why there may be no assets in response (if the selection was cancelled, etc) but why would all the fields be possibly null? Surely some of these will always be defined right?