output_metadata_list recent trend is getting deleted after adding a new class.

[realbp]

@seankross
could you take a look at get-metadata.R lines 86 - 137?
https://github.com/getwilds/cancerprof/blob/646a242744f5422fc36283be61f01ef2db8faddb/R/get-metadata.R#L86C1-L137

I am trying to add recent_trends as a dataframe inside a list of strings. On line 119, output_metadata_list prints out correctly, but once I add the new class on line 135, recent_trends disappears from output_metadata_list.