[BUG] Maximum call stack size exceeded when mounting, certain options not working

[LorduFreeman]

Describe the bug
Tested in a fresh new DnD5 world with only the needed modules activated.

Uncaught (in promise) RangeError: Maximum call stack size exceeded
    at mergeObject (foundry.js:1177)
    at mergeObject (foundry.js:1226)
    at mergeObject (foundry.js:1226)
    at mergeObject (foundry.js:1226)
    at mergeObject (foundry.js:1226)
    at mergeObject (foundry.js:1226)
    at mergeObject (foundry.js:1226)
    at mergeObject (foundry.js:1226)
    at mergeObject (foundry.js:1226)
    at mergeObject (foundry.js:1226)

In console when mounting, mounting works but automatically moving the rider to the set position does not, same for moving the rider to dismount

Environment Details
Foundry VTT Version: 0.7.9
DnD5e: 1.2.4
Mount Up! Version: 3.1.5
libWrapper: 1.5.2.0
TokenAttacher: 4.0.2

To Reproduce
Steps to reproduce the behavior:

1. Put a starter hero and warhorse next to each other
2. select both tokens
3. press mount button