[2023] Javascript error with launcher keeping me from playing

Please run these Windows repair tools:

.NET

Microsoft .NET Framework Repair Tool is available - Microsoft Support

Describes the .NET Framework Repair Tool and how to obtain it. support.microsoft.com
SCANNOW:

Use the System File Checker tool to repair missing or corrupted system files - Microsoft Support

Describes how to use the System File Checker tool to troubleshoot missing or corrupted system files in Windows 8.1, Windows 8, Windows 7 or Windows Vista. support.microsoft.com

THEN Please try this:

- uninstall Paradox Launcher v2 from the Windows "Apps and features" utility, if still present.

Delete the following folders if still present:

- C:/users/{userName}/AppData/Local/Programs/Paradox Interactive/
- C:/users/{userName}/AppData/Local/Paradox Interactive/
- C:/users/{userName}/AppData/Roaming/Paradox Interactive/launcher-v2/
To see the AppData folder you'll need to enable View Hidden Items in File Explorer.

- exit the Steam app entirely
- run steam.exe as the Windows Admin user
- run the game from the PLAY button in Steam
OR
- exit the Epic app entirely
- run EpicGamesLauncher.exe as the Windows Admin user
- run the game from the Epic client

IF that doesn't help, in this folder are some .log files:
C:/users/{userName}/AppData/Local/Paradox Interactive/launcher-v2/
Please attach them here.

Note that you can run ck3.exe directly from File Explorer, which bypasses the launcher.  

Right click on this game in your Steam Library, manage, browse local files. Then go into the Binaries folder, ck3.exe is there. Does it work if you double click on it, or give an error?  

There's been a new launcher release now. Please do the clean reinstall of it I described above, again. Any different?  

I don't know then. What if you make a new Windows user on this machine and log into it with that? Do you get the same problem?