fix: bad error passing webContents.print(null)

[codebytere]

Description of Change

Fixes #38598.

Fixes an issue where passing webContents.print(null) would trigger the following error:

Cannot read properties of null (reading 'pageSize').

This was happening because we weren't properly validating options.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fixes an issue where passing webContents.print(null) could incorrectly trigger an error.

[ckerr]

Not a blocker to the PR; asking for my own info: what's the difference between the default = {} argument in the old code and the options = printOptions ?? {} code? Is this to safeguard against an explicit null being passed as the first argument, or...?

[codebytere]

@ckerr default arguments only take effect if the no value or undefined is passed, so when they user passes in null they're bypassed entirely . This change (and using ?? specifically) ensures it's defaulted if it's null or undefined.

Old but nevertheless interesting article about falsy value handling patterns: https://medium.com/@bmb21/default-parameters-and-nulls-in-javascript-9149c8d26b0a

[release-clerk]

Release Notes Persisted

Fixes an issue where passing webContents.print(null) could incorrectly trigger an error.

[trop]

I have automatically backported this PR to "24-x-y", please check out #38640

[trop]

I have automatically backported this PR to "26-x-y", please check out #38641

[trop]

I have automatically backported this PR to "25-x-y", please check out #38642