Bug with Tab Widget? (in combination with datepicker)

Hi folks,
I've noticed a strange behaviour in my living application and started striping down my page.
The datepicker does not work (it does nothing, no popup - see error trace below).
I could nail it down to the tab widget (at least it seems to produce the error, I don't know if the same happens with other widgets).

So to test: Create e page, insert a date widget, test it. Then insert a Tab widget, test it again.
It doesn't care where you place your date widget.
This is what I get in the console:

Error: a.replace is not a function
a@http://localhost:8080/designer/generator/js/vendor.min.js:292:4165
this.$get</<@http://localhost:8080/designer/generator/js/vendor.min.js:292:4677
u@http://localhost:8080/designer/preview/page/03e893a3-d857-4161-b76b-2daf...
.link@http://localhost:8080/designer/preview/page/03e893a3-d857-4161-b76b-2daf...
Xc@http://localhost:8080/designer/generator/js/vendor.min.js:70:279
x@http://localhost:8080/designer/generator/js/vendor.min.js:59:323
g@http://localhost:8080/designer/generator/js/vendor.min.js:51:409
g@http://localhost:8080/designer/generator/js/vendor.min.js:51:426
x@http://localhost:8080/designer/generator/js/vendor.min.js:59:267
g@http://localhost:8080/designer/generator/js/vendor.min.js:51:409
g@http://localhost:8080/designer/generator/js/vendor.min.js:51:426
x@http://localhost:8080/designer/generator/js/vendor.min.js:59:267
g@http://localhost:8080/designer/generator/js/vendor.min.js:51:409
x@http://localhost:8080/designer/generator/js/vendor.min.js:59:267
g@http://localhost:8080/designer/generator/js/vendor.min.js:51:409
x@http://localhost:8080/designer/generator/js/vendor.min.js:59:267
g@http://localhost:8080/designer/generator/js/vendor.min.js:51:409
Q/<@http://localhost:8080/designer/generator/js/vendor.min.js:51:17
$/<@http://localhost:8080/designer/generator/js/vendor.min.js:52:395
l@http://localhost:8080/designer/generator/js/vendor.min.js:56:399
ne</<.link/<@http://localhost:8080/designer/generator/js/vendor.min.js:217:335
Ue/this.$get</m.prototype.$digest@http://localhost:8080/designer/generator/js/vendor.min.js:124:112
Ue/this.$get</m.prototype.$apply@http://localhost:8080/designer/generator/js/vendor.min.js:127:10
xc/d/<@http://localhost:8080/designer/generator/js/vendor.min.js:17:477
e@http://localhost:8080/designer/generator/js/vendor.min.js:36:313
xc/d@http://localhost:8080/designer/generator/js/vendor.min.js:17:1
xc@http://localhost:8080/designer/generator/js/vendor.min.js:18:179
Od@http://localhost:8080/designer/generator/js/vendor.min.js:17:1
@http://localhost:8080/designer/generator/js/vendor.min.js:252:171
a@http://localhost:8080/designer/generator/js/vendor.min.js:165:217
qf/c@http://localhost:8080/designer/generator/js/vendor.min.js:32:384

Any ideas? Help would be highly appreciated!
Thank you