fix: return fallback if value cannot be parsed

If there is a fallback we should handle this error more gracefully.
We report it in the console, but return the fallback if provided.
Otherwise we just throw as before.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

Author: susnux

eslint.config.js

@@ -6,4 +6,12 @@
 import { recommendedLibrary } from '@nextcloud/eslint-config'
 import { defineConfig } from 'eslint/config'
 
-export default defineConfig([...recommendedLibrary])
+export default defineConfig([
+	...recommendedLibrary,
+	{
+		rules: {
+			// this is quite a lowlevel library without dependencies - so no dependency on the logger
+			'no-console': 'off',
+		},
+	},
+])

lib/index.ts

@@ -31,6 +31,11 @@ export function loadState<T>(app: string, key: string, fallback?: T): T {
 		window._nc_initial_state.set(selector, parsedValue)
 		return parsedValue
 	} catch (error) {
+		console.error('[@nextcloud/initial-state] Could not parse initial state', { key, app, error })
+
+		if (fallback !== undefined) {
+			return fallback
+		}
 		throw new Error(`Could not parse initial state ${key} of ${app}`, { cause: error })
 	}
 }

test/index.test.ts

@@ -46,3 +46,31 @@ test('returns cached value with consequent calls', () => {
 
 	expect(JSON.parse).toHaveBeenCalledTimes(1)
 })
+
+test('throws if state cannot be parsed and no fallback is provided', () => {
+	const errorLog = vi.spyOn(console, 'error')
+	errorLog.mockImplementationOnce(() => {})
+
+	appendInput('app', 'key', 'value')
+	const spy = vi.spyOn(JSON, 'parse')
+	spy.mockImplementationOnce(() => {
+		throw new Error('mocked parsing exception')
+	})
+
+	expect(() => loadState('app', 'key')).toThrowError('Could not parse initial state key of app')
+	expect(errorLog).toHaveBeenCalledOnce()
+})
+
+test('returns fallback if state cannot be parsed but fallback is provided', () => {
+	const errorLog = vi.spyOn(console, 'error')
+	errorLog.mockImplementationOnce(() => {})
+
+	appendInput('app', 'key', 'value')
+	const spy = vi.spyOn(JSON, 'parse')
+	spy.mockImplementationOnce(() => {
+		throw new Error('mocked parsing exception')
+	})
+
+	expect(loadState('app', 'key', 'fallback')).toBe('fallback')
+	expect(errorLog).toHaveBeenCalledOnce()
+})