Server hangs at startup when corrupted jar is in the local extension repository

I reproduced this issue on a 8.4.5, on an ubuntu (and a debian) with tomcat8 and, in one case oracle java 8 in the other case openjdk java 8.

It should reproduce using the following steps:

• install CKEditor extension version 1.25 on the wiki
• in the extension/repository folder, in the corresponding subfolders, replace one of the webjar or plugin of ckeditor jars with the one attached to this issue, without any other change
• restart the server

Actual result:

• wiki "starts" but trying to access the wiki from the browser results in infinite loading (followed by a timeout if there is an apache in front or some other server that would display timeouts)
• the container displays in the console: "deploying application /xwiki" and doesn't display "done deploying wiki" (actually sometimes it does display, sometimes it doesn't)
• nothing else happens, no logs are displayed

Possible expected results:

• server starts and wiki is accessible from browser but the extensions with invalid jars are not loaded
• server starts and wiki is accessible from browser and logs an error in the logs about the invalid extension