Empty blocks are confusing highlighting and error checking

[cholick]

Example of incorrect highlighting

given:
def a = 1

when:

In the above code, when is not highlighted.

Example of incorrect error checking

given:

when:
def a = 1
a++

then:
a == 2

In the above code, the then is highlighted as given must be followed by... It looks like the when is being parsed as part of the given block.