fix: ignore empty or invalid timezone tag params

src/Events.php

@@ -4,6 +4,7 @@
 
 use Carbon\CarbonImmutable;
 use Carbon\CarbonInterface;
+use DateTimeZone;
 use Exception;
 use Illuminate\Pagination\Paginator;
 use Illuminate\Support\Collection;
@@ -43,7 +44,7 @@ class Events
 
     public static function defaultTimezone(): string
     {
-        return static::setting('timezone');
+        return static::resolveTimezone();
     }
 
     public static function fromCollection(string $handle): self
@@ -56,6 +57,17 @@ public static function fromEntry(string $id): self
         return new static(new Parameters(['event' => $id]));
     }
 
+    public static function resolveTimezone(mixed $timezone = null): string
+    {
+        return collect([
+            $timezone,
+            static::setting('timezone'),
+            config('statamic.system.display_timezone'),
+            config('app.timezone'),
+            'UTC',
+        ])->first(fn (mixed $candidate) => static::isValidTimezone($candidate));
+    }
+
     public function __construct(Parameters $params)
     {
         throw_if(
@@ -71,7 +83,7 @@ public function __construct(Parameters $params)
             ->offset(offset: $params->int('offset'))
             ->pagination(page: Paginator::resolveCurrentPage(), perPage: $params->int('paginate'))
             ->sort($params->get('sort', 'asc'))
-            ->timezone(timezone: $params->get('timezone', static::defaultTimezone()));
+            ->timezone(timezone: $params->get('timezone'));
     }
 
     public static function setting(string $key, $default = null): mixed
@@ -172,9 +184,9 @@ public function terms(string|array $terms): self
         return $this;
     }
 
-    public function timezone(string $timezone): self
+    public function timezone(?string $timezone = null): self
     {
-        $this->timezone = $timezone;
+        $this->timezone = static::resolveTimezone($timezone);
 
         return $this;
     }
@@ -195,6 +207,21 @@ public function upcoming(int $limit = 1): EntryCollection|LengthAwarePaginator
         );
     }
 
+    private static function isValidTimezone(mixed $timezone): bool
+    {
+        if (! is_string($timezone) || ! filled($timezone)) {
+            return false;
+        }
+
+        try {
+            new DateTimeZone($timezone);
+        } catch (Exception) {
+            return false;
+        }
+
+        return true;
+    }
+
     private function output(callable $type, string|CarbonInterface $from): EntryCollection|LengthAwarePaginator
     {
         $occurrences = $this->entries()->occurrences(generator: $type, from: $from);

src/Tags/Events.php

@@ -38,7 +38,7 @@ public function calendar(): Collection
 
         $month = $this->params->get('month', now()->englishMonth);
         $year = $this->params->get('year', now()->year);
-        $timezone = $this->params->get('timezone', Generator::defaultTimezone());
+        $timezone = Generator::resolveTimezone($this->params->get('timezone'));
 
         $from = parse_date($month.' '.$year)->shiftTimezone($timezone)->startOfMonth()->startOfWeek();
         $to = parse_date($month.' '.$year)->shiftTimezone($timezone)->endOfMonth()->endOfWeek();

tests/Tags/EventsTest.php

@@ -8,6 +8,7 @@
 use Statamic\Facades\Site as SiteFacade;
 use Statamic\Sites\Site;
 use Statamic\Support\Arr;
+use TransformStudios\Events\Events;
 use TransformStudios\Events\Tags\Events as EventsTag;
 
 beforeEach(function () {
@@ -663,6 +664,42 @@
         ->first()->start->timezone->getName()->toBe('America/Vancouver');
 });
 
+it('falls back to the default timezone when the timezone param is empty', function () {
+    Carbon::setTestNow(now()->setTimeFromTimeString('10:00'));
+
+    $this->tag
+        ->setContext([])
+        ->setParameters([
+            'collection' => 'events',
+            'from' => Carbon::now()->subDay(),
+            'timezone' => '',
+            'to' => Carbon::now()->addDays(2),
+        ]);
+
+    $occurrences = $this->tag->between();
+
+    expect($occurrences)->toHaveCount(1)
+        ->first()->start->timezone->getName()->toBe(Events::defaultTimezone());
+});
+
+it('falls back to the default timezone when the timezone param is invalid', function () {
+    Carbon::setTestNow(now()->setTimeFromTimeString('10:00'));
+
+    $this->tag
+        ->setContext([])
+        ->setParameters([
+            'collection' => 'events',
+            'from' => Carbon::now()->subDay(),
+            'timezone' => 'not-a-real-timezone',
+            'to' => Carbon::now()->addDays(2),
+        ]);
+
+    $occurrences = $this->tag->between();
+
+    expect($occurrences)->toHaveCount(1)
+        ->first()->start->timezone->getName()->toBe(Events::defaultTimezone());
+});
+
 it('sets "spanning"', function () {
     Carbon::setTestNow(now()->setTimeFromTimeString('10:00'));