Oh yes, I forgot to copy the error message in here. Sorry about that, I wrote that post right before going to bed after trying to find what causes it.
Here it is:
Assertion failure: Calling expvalue.set_float without number type
Stack trace:
assert2@http://192.168.178.49:50000/preview_prelude.js:16:10
ExpValue.prototype.set_float@http://192.168.178.49:50000/expressions.js:898:3
Exps.prototype.PeerState@http://192.168.178.49:50000/Multiplayer_plugin.js:1678:3
ExpNode.prototype.eval_object_exp@http://192.168.178.49:50000/expressions.js:347:22
Parameter.prototype.get_exp@http://192.168.178.49:50000/eveng.js:2059:3
Condition.prototype.run_system@http://192.168.178.49:50000/eveng.js:1262:22
EventBlock.prototype.run@http://192.168.178.49:50000/eveng.js:868:18
EventBlock.prototype.run_subevents@http://192.168.178.49:50000/eveng.js:996:5
EventBlock.prototype.run_actions_and_subevents@http://192.168.178.49:50000/eveng.js:935:3
EventBlock.prototype.run@http://192.168.178.49:50000/eveng.js:888:4
EventBlock.prototype.run_subevents@http://192.168.178.49:50000/eveng.js:996:5
EventBlock.prototype.run_actions_and_subevents@http://192.168.178.49:50000/eveng.js:935:3
EventBlock.prototype.run@http://192.168.178.49:50000/eveng.js:888:4
EventBlock.prototype.run_subevents@http://192.168.178.49:50000/eveng.js:996:5
EventBlock.prototype.run_actions_and_subevents@http://192.168.178.49:50000/eveng.js:935:3
EventBlock.prototype.run@http://192.168.178.49:50000/eveng.js:888:4
EventSheet.prototype.run@http://192.168.178.49:50000/eveng.js:224:4
Runtime.prototype.logic@http://192.168.178.49:50000/preview.js:2663:4
Runtime.prototype.tick@http://192.168.178.49:50000/preview.js:2350:3
Runtime.prototype.initRendererAndLoader/this.tickFunc@http://192.168.178.49:50000/preview.js:658:42
Subsequent failures will now be logged to the console.