> union(tibble(a = 1), tibble(a = "1"))
Error: not compatible: 
- Incompatible types for column `a`: double vs character

> union(tibble(a = 1, b = 2), tibble(a = "1", b = "2"))
Error: not compatible: 
- Incompatible types for column `a`: double vs character
- Incompatible types for column `b`: double vs character

