Hi Carl,
I have checked with even different template(responsive_classic) and still I am getting the same error.
The site is very simple, does not used any other javascript/jquery other than that is used in opc and square web that is given.
I dont find any issue in dev tools as advised.
Is there anyone who implemented this new plugin in live store(1.5.7d) also used square web pay.

dev tool result attached for reference.
https://prnt.sc/eE_9nMMT-GH4

Thanks
Balaji