In a Firefox extension, if I open a tab using a custom scheme, how do I close it, because my extension is not authorized for that scheme pattern? - firefox-addon

Question

I have a custom scheme mapped on my Windows machine: "dbn".
So, when I put dbn:/some/arguments in the Firefox address bar (or click on such a link), it launches in another application. This works great.
However, in a Firefox extension, I don't know how to "call" or "activate" this custom scheme except by opening a new tab, like this:
browser.tabs.create({ url: 'dbn:/some/arguments' });
That works fine, except now I have an open tab with dbn:/some/arguments as the URL. I have attempted to subsequently close it from my extension, but I can't because:
Error: Missing host permission for the tab
My extension doesn't have permissions for that "host."
I have tried to give it permissions via a match_patterns value of dbn:* but that throws an error when I try to reload the extension because those values apparently have to use one of the expected schemes (http, https, ftp, etc.).
I end up just having to close the tab manually, which isn't terrible, but is clearly sub-optimal.
So, two questions:
Is it possible to "call" a URL in such a way to activate a custom-mapped scheme on Windows without opening a tab? The only way I could think of doing this in such a way that it would activate my mapped command was to open a tab, but are there other ways?
If opening a new tab is the only way to do this, how do I close the tab I just opened without having the permissions problem I mention above?
Update
I don't think it's permissions anymore. The Promise simply won't resolve.
browser.tabs.create({ url: "some/url" })
.then(tab => console.error("I never get here"));
I've debugged up, down, and sideways. The new tab opens, and I can write to the log all around that operation, but the code in then just doesn't execute, no matter what I put in there. I tried to trap an error with try...catch, but that didn't trap anything.
I now think that permission above was coming from a different extension, not my extension. I don't think this has anything to do with the host.

Answer 1

AFA custom schemes, there is an open bug: Extend match patterns to handle custom protocol schemes
You can tabs.remove() a tab by its ID which you get from tabs.create().
async function fun() {
// note this is async
const tab = await browser.tabs.create({url: 'dbn:/some/arguments'});
// later remove it
browser.tabs.remove(tab.id);
}
// or
browser.tabs.create({url: 'dbn:/some/arguments'})
.then(tab => {
// do what is needed
// later remove it
browser.tabs.remove(tab.id);
});
Update:
Regarding the Promise, there is not enough information to pinpoint the issue.
Which permissions have been set?
Where is the code running?
Use catch to get more info about the Promise failure:
browser.tabs.create({url: "some/url"})
.then(tab => console.log(`Created new tab: ${tab.id}`))
.catch(error => console.log(error.message));