If you check the output log,
you can see the errors in there.
That is indeed a mismatch between GMLive and GMS2, though that is interesting - that syntax was not allowed when I last checked, as GM <= 8 did not require commas between variable names in declarations, so you could do
var a b c
var a, b, c
Then in GM8.1 ability to initialize local variables was added, but the space syntax still stayed, so
var a, b
c = 1
would compile as
var a, b, c = 1
which was making a pretty big mess in some cases.
So the compiler was later made to show an error when trying to do that.
That error then stayed in GMS since people would still import projects with old-style code.
It is good that it was eventually removed though. I'll get rid of that alert in the next version then.