I tried to send line~ from throw~ to catch~ but it gives me "catch~: no method for 'float'" is it normal behavior or a bug? And if normal, what I'm doing wrong? Line~ has audio connections so it is logical to think that signal can be sent via trew~/catch~ method?

are you sure you're sending [line~] and not [line] (control version?)
it's working over here..

Interesting. .. it is not possible to connect the audio out to control in, but it is possible to SEND audio via throw~ to toggle inlet, and that gives me "no method for float" error.