make eslint happy

What does this PR do?

Fix some linting problems created by previous changes (mostly mine). Also add some types to chiptune2.ts so the typechecker is happier.

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requested review from @luna, @tess, and @Leah

typechecker and linter seems happier, chiptune player still functions, notification settings look the same and catspeak still works (both latin and korean), lgtm! ^^

approved this merge request

approved this merge request

merged

mentioned in commit 84a98e41