How to reproduce:
1. Open the attached project "Test"
2. Open the "SampleScene" scene
3. Make sure to have the "Animator" tab opened and select the "Test1" GameObject in the Hierarchy
4. Select the transition between the "Test1" and "test1_2" animations
5. Click the "+" button to add a condition
6. In the Animator window, delete the parameter "test" and create another parameter
7. Select the Transition again and observe the Conditions tab

Expected results: The Conditions window shows only "Parameter does not exist in Controller"
Actual results: The Conditions window shows the empty dropdown and the warning at the same time

Reproducible with: 2022.3.58f1, 6000.0.40f1, 6000.1.0b8, 6000.2.0a5

Reproducible on: macOS Sequoia 15.3
Not reproducible on: No other environment tested

Note: When the only Parameter is deleted and another one is not added, the empty dropdown is not displayed