Assigning resource properties to setup a cyclical dependency can lead to a crash

[Phischermen]

Godot version:
Godot 3.2.3 rc3

OS/device including version:

Windows

Issue description:

While editing a resource, I mis-clicked and accidentally assigned the wrong file to the script property. This file happened to be the resource I was editing in the inspector. I got a warning telling me that the type was not expected. Immediately afterwards, the engine froze and crashed.

I did some debugging and discovered that the crash was caused by a stack overflow exception. This happened because the program was trying to hash the resource in a recursive method (Resource::hash_edited_version) that required the hash of the same resource. I also discovered that setting resource properties to create a cyclical dependency causes the engine to freeze and then crash. I expected the editor to prevent the user from setting up cyclical dependencies in resources, due to its instability.

Steps to reproduce:

Crash 1 - Setting script to self

1. Download sample project
2. Open test_resource1.tres
3. Set script to "test_resource1.tres"
4. A warning will popup, and then the editor will crash

Crash 2 - Creating cyclical dependency

1. Download sample project
2. Open test_resource2.tres
3. Set property named "Crash" to test_resource3.tres
4. Open test_resource3.tres
5. Set property named "Crash" to test_resource2.tres
6. Editor will freeze and eventually crash

Minimal reproduction project:

ResourceCyclicalDependencyIssue.zip

[Calinou]

See also #44195 and #39153.