Wrapper script, attempts to execute Slack with the correct URI argument.
The electron environment in Tumbleweed seems to suffer from a flaw similar to kde-open5 [1], that results in Slack failing to open the workspace correctly. It mangles the host part of the URI into lowerspace, which is Slack's undoing.
Generic URL handling is defined in RFC 3986: URI Generic Syntax, where section 3.2.2 says: "The host subcomponent is case-insensitive"). The electron environment appears to conform with that in newer releases.
The simplest place to solve this would be also on the Slack side by accepting a lower case host part of the internal slack:// URI, or it shouldn't use any host part at all (slack:///...).
Since they are aware of this issue since several month, we cannot rely on a fix provided anytime soon [3], so here's a (hopefully) suitable antidote.
[1] KDE issue: https://bugs.kde.org/show_bug.cgi?id=429408 [2] https://www.rfc-editor.org/rfc/rfc3986 [3] With the usual outcome: we do not support openSUSE Tumbleweed, use the snap packages! Needless to say, they suffer from the same issue.