Editor crash during atlas creation process

[NaejDoree]

Tested versions

Reproductible in 4.4.1
Non reproductible in 4.3

System information

Windows 10

Issue description

I you leave the atlas file field empty while importing multiple sprites as atlas in multi select and hit reimport it leads to the editor freezing indefinitely or crashing
The project will fail to open after this until you revert the import setting.

Steps to reproduce

• Add 2 png files to your project
• Go in the import tab with the png files selected (in multi select)
• Change their import setting to TextureAtlas
• Hit reimport

Minimal reproduction project (MRP)

atlas-bug-minimal-repro.zip

[NaejDoree]

I also had a few other issues with weird behaviour of the editor when creating atlases in multi select or not, but the others have unreliable behaviours so far. I'll try to create an issue for specific bugs if I find consistent repros of those, but I'm most likely going to avoid this feature to go forward on my work without dealing with the bugs

[NaejDoree]

Here is an other issue in the atlas creation process:
#107499

[rsubtil]

Can confirm in Windows it freezes on v4.4.1.stable, finishes "successfully" on v4.3.stable but cannot reproduce this case on Linux. EDIT: It happens on Linux too, I had mismatched versions while testing.

⚙ Bisecting...

[rsubtil]

Bisected to 1b0c5cb (#93064), cc @Hilderin

This time I did leave it running for ~10min, so it seems the editor is really freezing, and not just taking a long time to process this import.