Communication Diagram : Arrows for communication link messages are not displayed correctly in pdf export

[fh314]

Describe the bug

When exporting a communication diagram as pdf, the arrows indicating the direction of a message on a communication link are not displayed correctly. This happens when using Apollon standalone 1.5.1. I'm not sure if this issue should be moved to the standalone repo

To Reproduce

1. Create two objects with communication link between them
2. Add a message to the communication link
3. Export diagram as pdf
4. See error

Expected behavior

The arrows should be displayed in the pdf as they are in the editor

Screenshots

In editor:

In pdf:

Environment

 - OS: Windows 10
 - Browser: Chrome
 - Version 104.0.5112.79
 - On https://apollon.ase.in.tum.de/

Additional context

Output in Web Console

  [REPLACE THIS WITH YOUR INFORMATION]

[fh314]

Happens for both Acrobat DC and Chrome pdf view