how to put a declaration in a if-function?

Question

hey community, 

 

I am making a pdf with information from a website. My problem is the image. If there is an image it works with the codes:

const first_picture_url: string = product.pictures[0].url;
const other_picture_urls: string[] = product.pictures.filter(

(_: { url }, index: number) => index > 0).map((picture: { url }) => picture.url);

If there is no image, i get the Error 

TypeError: Cannot read property 'url' of undefined.

 

 i found out i could prevent this with

if(product.pictures.length<1)

 but if i try to put the first codes in this if-function it doesnt work.

 

My try:

if(product.pictures.length>0){
      const first_picture_url: string = product.pictures[0].url;
      const other_picture_urls: string[] = product.pictures.filter(

       (_: { url }, index: number) => index > 0).map((picture: { url }) => picture.url);
}
 else
{
      const first_picture_url: string = String(product.airCoolingIntegrated);
}

it doesnt work, i get the message  "first_picture_url" is declared but its value is never read"

 

i just want these lines not be initiated if the length of the attribute is 0. (so no picture existing).

 

Can anyone help me with that maybe?

 

Greetings