36 lines
1.2 KiB
TypeScript
36 lines
1.2 KiB
TypeScript
// Copyright 2018-2020 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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const stringify = (value: unknown): string => {
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try {
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// `JSON.stringify` can return `undefined` (TypeScript has incorrect types here).
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// However, this is fine because we interpolate it into a string, so it shows up as
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// "undefined" in the final error message.
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return JSON.stringify(value);
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} catch (err) {
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return Object.prototype.toString.call(value);
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}
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};
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// `missingCaseError` is useful for compile-time checking that all `case`s in
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// a `switch` statement have been handled, e.g.
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//
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// type AttachmentType = 'media' | 'documents';
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//
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// const type: AttachmentType = selectedTab;
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// switch (type) {
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// case 'media':
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// return <MediaGridItem/>;
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// case 'documents':
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// return <DocumentListItem/>;
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// default:
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// return missingCaseError(type);
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// }
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//
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// If we extended `AttachmentType` to `'media' | 'documents' | 'links'` the code
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// above would trigger a compiler error stating that `'links'` has not been
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// handled by our `switch` / `case` statement which is useful for code
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// maintenance and system evolution.
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export const missingCaseError = (x: never): TypeError =>
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new TypeError(`Unhandled case: ${stringify(x)}`);
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