BigQuery ARRAY_TO_STRING based on condition in non-array field

Question

I have a table that I query like this...

select *
from table
where productId = 'abc123'

Which returns 2 rows (even though the productId is unique) because one of the columns (orderName) is an Array...

**productId, productName, created, featureCount, orderName**
abc123, someProductName, 2020-01-01, 12, someOrderName
      ,                ,           ,   , someOtherOrderName

I'm not sure whether the missing values in the 2nd row are empty strings or nulls because of the way the orderName array expands my search results but I want to now run a query like this...

select productName, ARRAY_TO_STRING(orderName,'-')
from table
where productId = 'abc123'
and ifnull(featureCount,0) > 0

But this query returns...

someProductName, someOrderName-someOtherOrderName

i.e. both array values came back even though I specified a condition of featureCount>0.

I'm sure I'm missing something very basic about how Arrays function in BigQuery but from Google's ARRAY_TO_STRING documentation I don't see any way to add a condition to the extracting of ARRAY values. Appreciate any thoughts on the best way to go about this.