Reproduction steps:
1. Create a new project
2. Install Visual Effect Graph package
3. Create Visual Effect Asset (Create > Visual Effects > Visual Effect Graph)
4. Double-click on the Asset to open VFX Graph, select a template to insert and press “Create” button
5. Press on the dropdown icon next to “Insert a template into current graph” button and select “Insert template”
6. Observe the Console

Actual result: 
{code:java}
GUI Window tried to begin rendering while something else had not finished rendering! Either you have a recursive OnGUI rendering, or the previous OnGUI did not clean up properly.{code}
error is thrown
Expected result: No warnings or errors are thrown

Reproducible with: 6000.0.60f1, 6000.2.9f1
Not reproducible with: 6000.3.0b7, 6000.4.0a3
Couldn’t reproduce with: 2022.3.68f1 (No “Insert template” option)

Reproduced on: Windows 11
Not reproduced on: macOS Sequoia 15.4 (M4), Ubuntu 22.04

Note: Issue is not reproducible if “Insert a template into current graph” button is pressed instead