Firefox extension Javascript errors logged in console

When I start Firefox I get a string of mainly javascript errors logged in the console. These errors then repeat at regular intervals. Not sure when this started, but just noticed my console log was full of error messages from Firefox! Had a quick search here and on Goggle and didn't turn up similar reports (apologies if this is logged elsewhere though). I'm using Firefox 19.0.2 with 1password extension 3.9.10 on Mac OS X 10.6.8.

Extract from Console log:

29/03/2013 16:20:13 [0x0-0x131131].org.mozilla.firefox[8898] info: onepassword: [DATASOURCE] Database version: 7
29/03/2013 16:20:13 [0x0-0x131131].org.mozilla.firefox[8898] info: onepassword: [AGENT] connected to port 6258
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] error: onepassword: An exception occurred.
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] NS_NOINTERFACE: Component returned failure code: 0x80004002 (NS_NOINTERFACE) [nsIInterfaceRequestor.getInterface]
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] undefined 183
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] Traceback (most recent call last):
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] File "resource://onepassword-at-agilebits-dot-com/addon-sdk/lib/sdk/tabs/utils.js", line 183, in getTabForContentWindow
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] .getInterface(Ci.nsIWebNavigation)
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] File "resource://onepassword-at-agilebits-dot-com/addon-sdk/lib/sdk/tabs/helpers.js", line 12, in getTabForWindow
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] let tab = getTabForContentWindow(win);
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] File "resource://onepassword-at-agilebits-dot-com/addon-sdk/lib/sdk/content/worker.js", line 517, in Worker<.tab
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] return getTabForWindow(this._window);
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] File "resource://onepassword-at-agilebits-dot-com/onepassword/lib/global.min.js", line 451, in null
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] function ub(a){var b;if(!a)a=M.activeTab;if(!(Ya(a).length>0)){b=a.attach(sb);tb.push(b);b.on("detach",function(){var a=tb,d=a.indexOf(b);d!=-1&&a.splice(d,1)});b.on("error",function(a){s(a)});b.port.on("message",function(a){var d=a.name;Ta(b.tab,d,a.message,i);d==="unloadDocument"&&b.destroy()});b.port.on("perform",function(a){try{Ua(b,a.command,a.params,function(d){b.port.emit("callback",{uuid:a.uuid,result:d})})}catch(d){s(d)}})}}
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] File "resource://onepassword-at-agilebits-dot-com/addon-sdk/lib/sdk/deprecated/events.js", line 153, in _emitOnObject
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] listener.apply(targetObj, params);
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] File "resource://onepassword-at-agilebits-dot-com/addon-sdk/lib/sdk/deprecated/events.js", line 123, in _emit
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] return this._emitOnObject.apply(this, args);
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] File "resource://onepassword-at-agilebits-dot-com/addon-sdk/lib/sdk/content/worker.js", line 560, in _onContentScriptEvent
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] this._port._emit.apply(this._port, arguments);
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] File "resource://onepassword-at-agilebits-dot-com/addon-sdk/lib/sdk/content/worker.js", line 228, in portEmit
29/03/2013 16:20:34 [0x0-0x131131].org.mozilla.firefox[8898] self._addonWorker._onContentScriptEvent.apply(self._addonWorker, arguments);