in packages/rum-core/src/common/utils.js [180:189]
function setLabel(key, value, obj) {
if (!obj || !key) return
const skey = removeInvalidChars(key)
let valueType = typeof value
if (value != undefined && valueType !== 'boolean' && valueType !== 'number') {
value = String(value)
}
obj[skey] = value
return obj
}