Change operator `||` to `??` where reading environmental valuable [Fixes #12057]

[HiroyukiNaito]

Change operator || to ?? where reading environmental valuable [Fixes #12057]

Description

When reading environmental valuables, it is safer to use '??' operator. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing

Related Issue

#12057

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[HiroyukiNaito]

@wackerow Thank you for the deep insight. I would change the code according to your description.

[HiroyukiNaito]

@wackerow I changed codes according to your advice.