Use locally destructured mungeUnderscores instead of opts.mungeUnderscores

[Copilot]

opts can be undefined (it's an optional param), so accessing opts.mungeUnderscores directly is unsafe. The value is already safely destructured with a false default earlier in the function.

Change

• scripts/generateTypeScriptDefinitions.js: Replace opts.mungeUnderscores with the locally destructured mungeUnderscores (which defaults to false via const {mungeUnderscores = false} = opts ?? {})

// Before
{mungeUnderscores: opts.mungeUnderscores}

// After
{mungeUnderscores}