[guilherme-praca]

Description

fn_dl_extract could print "OK" and return 0 without extracting anything:

• An unsupported MIME type matched none of the branches, so the if returned 0.
• In selective ZIP extraction (extractsrc set) the captured status came from rm -rf, hiding failures from unzip (e.g. extractsrc not in the archive) and from cp.

Changes:

• Add an else branch that fails with Unsupported archive type: <mime>.
• Chain unzip && cp inside the captured command, so either failure sets the exit code.
• Remove the temp directory only after exitcode is captured, so cleanup cannot mask a failure.
• Capture stderr (2>&1) of tar/unzip/cp, so the reason ends up in extractcmd and the script log instead of only on the terminal.
• Update the function header comment (it did not mention xz).

Fixes #5048

Affected servers: all servers that download archives through fn_dl_extract (install, update and fix modules, e.g. ts3, mta, fctr, xnt, jk2, steamcmd bootstrap).

Type of change

• Bug fix (a change which fixes an issue).
• New feature (a change which adds functionality).
• New Server (new server added).
• Refactor (restructures existing code).
• Chore (CI, workflows, tooling or other maintenance).
• Comment update (typo, spelling, explanation, examples, etc).

Testing

• Commands/tests run: sourced fn_dl_extract from develop and from this branch with stubbed print/log/exit functions and ran both against the same fixtures (tar.gz, tar.bz2, tar.xz, zip; truncated tar.xz and zip; plain text file; missing extractsrc for zip and tar.gz; read-only destination for selective zip). shellcheck -S warning lgsm/modules/core_dl.sh is clean.
• Result:

case	develop	this PR
valid tar.gz / tar.bz2 / tar.xz / zip, full and selective	OK, rc 0	OK, rc 0
truncated tar.xz / zip	FAIL, rc 2 / 9	FAIL, rc 2 / 9 (error now in log)
unsupported type (text/plain)	OK, rc 0, nothing extracted	FAIL, rc 1
selective zip, extractsrc missing	OK, rc 0	FAIL, rc 11
selective zip, cp fails	OK, rc 0	FAIL, rc 1
selective tar.gz, extractsrc missing	FAIL, rc 2	FAIL, rc 2

Temp directory is removed in every case. Also checked: a downloaded HTML error page (text/html) and a plain .tar now fail as unsupported.

• Callers: every caller passes .tar.gz, .tar.bz2, .tar.xz or .zip (install_server_files, fix_, core_steamcmd, update_, and all 55 entries in mods_list.sh), so none relied on the old silent success. file is a required dependency in every distro CSV.

Failure propagation and exitbypass

• Update path: fn_update_apply runs download and extraction in a subshell with exitbypass unset (command_update.sh), so a failed extraction stops the update.
• Not changed here: when exitbypass is set, core_exit.sh returns instead of exiting, so the caller keeps going. One reachable case is command_update.sh → exitbypass=1 command_start.sh → check_steamcmd.sh → fn_install_steamcmd, which would continue to chmod +x steamcmd.sh after a failed extraction. This is the same for every core_exit.sh call in core_dl.sh, and a return 1 alone would not help because the callers do not check the return status, so I left it out of this PR. Happy to follow up if you want a specific approach.
• Environment used (distro/version): Fedora 44, bash 5, GNU tar, unzip 6.0

Risk and rollback

• Risk level: low. Successful extractions behave the same; only paths that already failed silently now stop with an error. One intended change: in selective ZIP extraction (jk2, xnt) an unzip warning (exit 1) now fails, as it already did for full ZIP extraction. On success, tar/unzip warnings are no longer printed live.
• Rollback plan: revert this commit.

Breaking changes

• No breaking changes.
• Breaking changes included (describe below).

Documentation

• No documentation update required.
• User documentation update required (LinuxGSM-Docs).
• Developer documentation update required (LinuxGSM-Dev-Docs).

Checklist

• This pull request links to an issue ("Fixes", or "Related to" for a partial fix).
• This pull request uses the develop branch as its base.
• This pull request subject follows the Conventional Commits standard.
• This code follows the style guidelines of this project.
• I have performed a self-review of my code.
• I have provided a detailed enough description of this PR.