How to reproduce:
1. Create a new project
2. Install the Behavior package through Window → Package Manager → Unity Registry
3. Create 2 Behavior Graphs
4. Open one of the Behavior Graphs, create a “Run SubGraph“ node, and assign the other Graph
5. Connect the “On Start“ node to the “Run SubGraph“ node
6. Open the other Behavior Graph, create a “Run SubGraph“ node
7. Connect the “On Start“ node to the “Run SubGraph“ node
8. Observe the Editor

Expected results: The Editor handles nested behavior graphs
Actual results: The Editor becomes unresponsive, “Asset Import“ dialog box opens, and never finishes loading

Reproducible in: 1.0.11 (6000.0.54f1, 6000.1.13f1, 6000.2.0b11)
Not reproducible in: 1.0.10 (6000.2.0b11)
Could not test in: Any version (6000.3.0a1 - 6000.3.0a3) (Behavior package errors)

Reproduced on: Windows 11 Pro (24H2)
Not reproduced on: No other environment tested

Notes:
- Closing the editor by force and reopening the project, the Launch screen will get stuck on “Importing“
- After finishing importing the asset(s) once, it will begin importing them again, this time as the next iteration
- After step 5, a NullReferenceException error is thrown in the Console as well