Launcher's crashing as soon as Run Client option is selected

Hello,

I've been using MCreator for a long time, yet this issue is the first one I'm encountering with the "Run Client" button. Basically, each time I would press the "Run Client" green triangle button, the launcher would load up twice in a row (it fills up the Mojang loading bar two times) then get stuck on a very specific time, that is 3/4 of the completion bar ; and so at each trial. Right after that (the loading process isn't finished), there is this dirt block background screen where there is, instead of an usual message, a " ▌" blockchain (you know, the placeholder symbol that appears when an emoji can't be loaded) then completely crashes (it returns to Gradle idle mode).

Has anyone an answer or a solution to this issue?

With regards, 

Coliop