toLocaleString bug formatting currencies in Spanish

[eltercero]

We are using toLocaleString to handle number formatting to strings in several places and it seems that this is the way the browser JS engine handles the Spanish locales:

It only happens with numbers from 1000 to 9999. 10000 is properly formatted to 10.000.

It's kind of recent.

More information: https://stackoverflow.com/questions/57628055/tolocalestring-not-working-on-numbers-less-than-10000-in-all-browsers