[DOC] JS Examples for avoiding errors on Smart Contracts Anatomy

[s-n-park]

Is your feature request related to a problem? Please describe. user submitted feedback of missing-info tag: "There are no JS examples on how to avoid errors on the page: https://docs.near.org/build/smart-contracts/anatomy/collections"

Describe the solution you'd like Updated docs to include examples on how to avoid errors on JS

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