ERA: Circular dependency error within a barrel method. Nothing obvious... not to me, anyway.

I have an ERA report, looks like up to date FW (unless I'm reading it wrong):

Error Name: Circular Dependency Error
Occurrences: 1
First Occurrence: 2020-06-12
Last Occurrence: 2020-06-12
Devices:
    vívoactive® 4: 4.70
App Versions: 0.0.6
Languages: gre
Backtrace:
    MonkeyBarrel_PartiallyObscure.makeSalt:118

But...

The method containing that line is a simple function that receives two strings, converts the strings using String.toUTF8Array() and then combines them into a third array, c, via a straightforward loop for (var i=0;i<len;i++) {}. Neither a, b or c exist outside of the method call and the strings are simple strings passed as arguments.

The value c is defined here:

var len = a.size(), blen = b.size(), c = new [len*2];

Then there is a loop that does some stuff, essentially combining values from a and b in order to generate c.

And as the line where the error occurs is this:

return c;

I am at a loss.

It sounds like it is a real problem with a real cause, but the only thread I found through searching with a similar barrel circular dependency was due to a problem with the barrel initialisation. That doesn't seem like it should be relevant here.

Anybody?

G