fix(site): handle missing default chart time (#2397)

Co-authored-by: henrygd <hank@henrygd.me>

internal/site/tests/chart-time.test.ts

@@ -0,0 +1,41 @@
+import { beforeEach, describe, expect, mock, test } from "bun:test"
+import type { UserSettings } from "../src/types"
+
+// lib/api needs a browser and the lingui macro transform, and stores only uses pb for the auth record
+mock.module("../src/lib/api", () => ({ pb: { authStore: { isValid: false, record: null } } }))
+
+const { $chartTime, $userSettings, defaultChartTime, getUserChartTime, hydrateUserSettings } = await import(
+	"../src/lib/stores"
+)
+
+describe("chart time from user settings", () => {
+	beforeEach(() => {
+		$chartTime.set(defaultChartTime)
+	})
+
+	test("hydration uses the stored chart time", () => {
+		hydrateUserSettings({ chartTime: "24h", emails: [] } as UserSettings)
+		expect($chartTime.get()).toBe("24h")
+	})
+
+	test("hydration falls back to the default when settings have no chart time", () => {
+		$chartTime.set("24h")
+		hydrateUserSettings({ emails: [] } as UserSettings)
+		expect($chartTime.get()).toBe(defaultChartTime)
+		expect(getUserChartTime()).toBe(defaultChartTime)
+	})
+
+	test("hydration falls back to the default when the stored chart time is empty", () => {
+		$chartTime.set("24h")
+		hydrateUserSettings({ chartTime: "", emails: [] } as unknown as UserSettings)
+		expect($chartTime.get()).toBe(defaultChartTime)
+		expect(getUserChartTime()).toBe(defaultChartTime)
+	})
+
+	test("other settings writes don't change the active chart time", () => {
+		$chartTime.set("12h")
+		$userSettings.set({ chartTime: "24h", emails: [], grid: true } as UserSettings)
+		$userSettings.setKey("chartTime", "7d")
+		expect($chartTime.get()).toBe("12h")
+	})
+})