Fix TS2322 type error in event-helpers.ts getNamespaceAndType method

[Copilot]

Resolves TypeScript compilation error TS2322 in PR #20847 where string | null was not assignable to keyof HTMLElementEventMap | null.

Changes

frontend/src/app/shared/helpers/event-helpers.ts

• Cast parts[1] to EventType | undefined before nullish coalescing to match return type signature
• Remove unnecessary as EventNamespace assertion (type alias to string)

// Before
const namespace = parts[0] as EventNamespace;
const type = parts[1] || null;

// After  
const namespace = parts[0];
const type = (parts[1] as EventType | undefined) ?? null;

The assertion is safe: NamespacedEvent is a template literal type ${EventType}.${EventNamespace} enforcing compile-time constraints on valid event names.

Original prompt

The TypeScript compilation errors in Pull Request #20847 (#20847) must be resolved. These errors include a TS2322 mismatch where 'string | null' is not assignable to 'keyof HTMLElementEventMap | null'. Additionally, object equality checks in JavaScript need to be updated to compare contents instead of identity. For example, replace 'x === []' with 'Array.isArray(x) && x.length === 0'. The fixes should ensure correct type handling and equality checks.

This pull request was created as a result of the following prompt from Copilot chat.

The TypeScript compilation errors in Pull Request #20847 (#20847) must be resolved. These errors include a TS2322 mismatch where 'string | null' is not assignable to 'keyof HTMLElementEventMap | null'. Additionally, object equality checks in JavaScript need to be updated to compare contents instead of identity. For example, replace 'x === []' with 'Array.isArray(x) && x.length === 0'. The fixes should ensure correct type handling and equality checks.

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[myabc]

Merged into #20847
Please continue work there.