Fix number replacement value returning an array instead of a string

[emileber]

Description

A regression was introduced following:

• Add interpolate option to react-i18n to support custom placeholder formats #2267

It was identified in another project where a test case expecting a string was failing since it was getting an array with the new @shopify/react-i18n version 7.1.0:

Expected: "Cannot be greater than 200 characters, current is 205 characters"
Received: ["Cannot be greater than ", 200, " characters, current is ", 205, " characters"]

Since this function is a little complex with a different return value type based on values inside the replacement dictionary, I've added 2 tests that validates the return value of translate.

That way, I caught another issue where an empty string was returned in the array when passing a React element as the last replacement value.

Type of change

• @shopify/react-i18n Patch: Bug (non-breaking change which fixes an issue)

Checklist

• I have added a changelog entry, prefixed by the type of change noted above (Documentation fix and Test update does not need a changelog as we do not publish new version)

[BPScott]

It seems that this was not a complete fix: https://buildkite.com/shopify/web-ci-builder/builds/482401