Different arguments for each.map vs each and map alone #9032

I found a difference between each.map and each / map

# jruby 10.0.2.0 (3.4.2) 2025-08-07 cba6031bd0 Java HotSpot(TM) 64-Bit Server VM 24.0.2+12-54 on 24.0.2+12-54 +indy +jit [arm64-darwin]
[[[1]]].each {|a,b| p [a,b] }     # [[1], nil]
[[[1]]].map {|a,b| p [a,b] }      # [[1], nil]
[[[1]]].each.map {|a,b| p [a,b] } # [1, nil] (should be the same as above two)

Actual code I was writing: array_of_tuple.each_slice(2).map {|a, b| ... }

Originally posted by @tompng in #8435