No feedback when running the postinstall from webui

[alexAubin]

Describe the bug

Run the postinstall from the webadmin : no logs are shown, it just hangs for a while during the postinstall, and then once it's complete you get the "Install complete"

Context

• Hardware: VPS, probably other platforms too
• YunoHost version: 11.0
• I have access to my server: SSH, webadmin

Expected behavior

See the postinstall messages while the postinstall gets run

Logs

The javascript console displays an error that may be related

[alexAubin]

Apparently this is also the case on buster ... So not a regression from bullseye

Still, this is an important issue