How to reproduce:
1. Start a local Perforce server with a valid user and a valid workspace
2. Create and open a new project
3. Open Project Settings from Edit > Project settings
4. Open the Version Control tab
5. Change Mode to Perforce
6. Fill in the correct Username, Password, and Server values
7. In the Workspace field type in a random string that isn't a Workspace name
8. Press the Connect button
9. Repeat step 8 until Unity crashes

Expected results: Unity throws errors in the Console window but doesn't crash
Actual results: Unity crashes

Reproducible with: 2020.1.0a23, 2020.1.6f1, 2020.2.0b2
Not reproducible with: 2018.4.27f1, 2019.4.10f1, 2020.1.0a22

Notes:
-Usually, 3-5 clicks are enough to crash the Editor
-If the button is clicked once but the Editor is left open, the Editor seems to crash after a few minutes with a different stack trace
-The full error which is being thrown when reproducing the bug:
Version Control: Perforce Version Control Plugin connected to Unity. Perforce connection is not online. Perforce client workspace not present on the Perforce server. Please check your Workspace setting in the Editor Settings.