I suspect this is due to the fact that typically humanize when it sees a zero delta, defaults to the plural timeframe (i.e second vs seconds). This causes an issue for these locales since the "zero" string for a timeframe is located in the non-plural timeframe unit within the timeframe object.
Issue Description
The Czech and Slovak locales fail when using Humanize on a delta of zero. See the following example below.
I suspect this is due to the fact that typically humanize when it sees a zero delta, defaults to the plural timeframe (i.e second vs seconds). This causes an issue for these locales since the "zero" string for a timeframe is located in the non-plural timeframe unit within the timeframe object.
System Info