On 20 Feb 2018, at 3:39, Evan Jones wrote:
Something's gone wonky with my Javascript bundle
(and only that one,
as far as I can tel)l. Every time I hit cmd-/ to comment/uncomment
some text, it uses an unindented block comment instead of the
double-slash single line comment I expect. ("/* */", rather than "//
")
[…]
A) how I could fix this particular issue, or
B) how I could remove all my changes to the Javascript bundle and
revert simply to the repo version?
In a JavaScript file select _Bundles → Select Bundle Item…_
(⌃⌘T) and switch to “Settings” then enter `comment`, you should
see something like this:

From this window, you can edit the settings, but any changes you have
made to the JavaScript (and other bundles) should be located in
`~/Library/Application Support/TextMate`. So a rough way to revert to
defaults is simply to remove that folder (or the bundles contained in
it).
I would still suggest first looking at the settings via the above
dialog, because the issue might also be that you installed a third party
bundle that override the comment settings for the JavaScript scope.