Just wasted too much time figuring out what was wrong with the following rather trivial line:
<Launch Condition="'$(Name)' = 'thebestname'" Message="no documentation for you"/>
This line results in the following error:
Error WIX0204 ICE03: Bad conditional string
It seems it should have single outer quotes and double innerquotes:
<Launch Condition='"$(Name)" = "thebestname"' Message="sillyness"/>
This is far from the only issue with Wix v4 I had which would have been avoided given decent documentation. If, like me, you do not have previous Wix experience and just want to dive in Wix v4, I strongly discourage you to do so.
For completeness, with a property (my actual use case) instead of a literal it looks like this:
<Launch Condition='"$(Name)" = THE_PROPERTY' Message="uh oh"/>
