[SalesForce] Did Salesforce recently update their aura library? Facing weird issues with access control and string concatenation

I am wondering whether Salesforce recently updated their lightning library outside of a release window – is there any way to verify the currently loaded version of aura/lightning?

Was led to asking this because I am facing two issues presently;

• It seems that having any custom 'rerender' method breaks the aura rendering cycle, getting this error message in my package org:

This page has an error. You might just need to refresh it. rerender
threw an error in 'markup://WSONE:svgIcon' [Access denied:
{"$from$":{"namespace":"WSONE"}}] Failing descriptor:
{markup://WSONE:svgIcon}

Versus in my development environment:

This page has an error. You might just need to refresh it. rerender
threw an error in 'markup://c:svgIcon' [Access denied:
{"Go":{"namespace":"c"}}] Failing descriptor: {markup://c:svgIcon}

• The second thing is that in some cases, at least for pages that did not exist previously in the package org, I receive a JSON parsing error which seems internal to the framework:

VM17613:957 Uncaught SyntaxError: Unexpected token u in JSON at
position 38441

Which occurs on "xhr.onreadystatechange" in lightning.out.delegate.js

Corresponding JSON line which errors out;

"code":function(cmp, fn) { return fn.add("slds-button slds-button--brand slds-path__mark-complete slds-no-flex slds-m-horizontal--small ",cmp.get("v.backCss")); },

Which corresponds to the following component definition line – if I remove that everything works as expected.

<button class="{!'slds-button slds-button--brand slds-path__mark-complete slds-no-flex slds-m-horizontal--small ' + v.backCss}" onclick="{!c.handlePreviousClick}">

If I remove that line it moves on to the next line where I use a composite expression – then the next and so forth – it seems to be a general problem with string concatenation because if I change like this the problem remains;

<button class="{!concat('slds-button slds-button--brand slds-path__mark-complete slds-no-flex slds-m-horizontal--small ', v.backCss)}" onclick="{!c.handlePreviousClick}">

However if I remove the concatenation all together it works just fine – my old components still seem to function mostly while they use concatenation as well…

Anybody have any clues what is going on here? I will try to mess around with different API versions of files now to see if that will make any difference – the new ones are v38.0 (but equal on the development org!) while old are 37.0.