browsertime: New Firefox HAR do not generate new pages in spa example

Hi @juliandescottes I could see one difference with the new HAR generation than before:

Using the script here, and running it with bin/browsertime.js spa.js -b firefox -n 1 (using the main branch)

I get errors in the log:

[2023-03-30 15:35:53] ERROR: Could not add meta data to the HAR, miss page 0
[2023-03-30 15:35:53] ERROR: Could not add meta data to the HAR, miss page 1

So somehow pages aren’t created in the HAR file. Looking the HAR I see: "pages":[],

Attached the HAR. spa.zip

Do you know if maybe we need to change something in Browsertime?