Ahh, ok, sorry, I obviously misread the details. The reason for the other site is likely the reason I stated. Your site …
The source of the error is coming from the WordPress Catalog plugin (guessing based solely on the error, could be another plugin).
Connections and its scripts are perfectly compatible with W3TC JS minification but when in combinations of n-number of plugins the minification can break things in unexpected ways.
My suggestion is to disable the JS minification to see if the issue resolves itself. It it does not, it is possible the JS minification was hiding another fatal JS error but I would not know what that is until the minification is turned off.
Hope that helps!