Description
When creating a message using the operator --++ the resulting lifeline on the receiver participant can't be deactivated directly after. Only after an additional message has been written deactivate works again. I think this is a bug, because when just using the ++ operator, the created lifeline can be deactivated directly after.

To Reproduce
Steps to reproduce the behavior:

1. Create a file for the plantuml code with the following lines of code:
   @startuml
   participant P1
   participant P2
   P1 -> P2 ++ : action
   deactivate P2
   |||
   P1 -> P2 --++ : action
   deactivate P2
   |||
   P1 -> P1 : action
   deactivate P2
   @enduml
2. generate the Sequence Diagram of this code

Expected behavior
I first included the behaviour of the program with just P1 -> P2 ++ : action. This creates a message to P2 and P2 starts a lifeline. Then the next line deactivates this lifeline, which we can see through |||, as there is a gap between the end of the lifeline and the next message. This is how I would expect the program to work. Now after that we have a message with --++. This also generates a lifeline, but unlike the example at the top, it isn't deactivated through the line after it, as it continues until the next message. Using the deactivate command after that will work again. I would expect that it'd work like the first example.

Desktop

• OS: Fedora 42
• Version 1.2025.2