Silent conversion of non existing output type to png

Question

When I use a command option line -tsomething (literarily) the resulting output is silently converted to a png file (with extension .png).

I think plantuml should not accept this option or at least give a warning that it is falling back to png.

Answer 1

Comand option always help to do some work.It very significant.

Comments

It is nice that an option always does something, but in case of wrong option this should be signaled.