fix(dav): map invalid CalDAV payloads to 400 instead of 500

extractTodo() throws Sabre\VObject\InvalidDataException for malformed ICS
or payloads that do not contain exactly one VTODO. That exception does not
extend Sabre\DAV\Exception, so the DAV server mapped it to 500 instead of
the 400 the PR description promises.

Catch it in CalendarObject::put() and rethrow as BadRequest, and cover the
put() mapping with a unit test.

Author: Jaggob

lib/DAV/CalendarObject.php

@@ -17,6 +17,7 @@
 use Sabre\DAV\Exception\NotFound;
 use Sabre\DAVACL\IACL;
 use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\InvalidDataException;
 
 class CalendarObject implements ICalendarObject, IACL {
 
@@ -78,6 +79,8 @@ public function put($data) {
 			$this->sourceItem = $this->backend->updateCardFromCalendarObject($this->sourceItem, $this->readPutData($data));
 		} catch (DoesNotExistException $e) {
 			throw new NotFound($e->getMessage(), 0, $e);
+		} catch (InvalidDataException $e) {
+			throw new BadRequest($e->getMessage(), 0, $e);
 		} catch (BadRequestException $e) {
 			throw new BadRequest($e->getMessage(), 0, $e);
 		} catch (StatusException $e) {

tests/unit/DAV/CalendarObjectTest.php

@@ -17,6 +17,7 @@
 use Sabre\DAV\Exception\BadRequest;
 use Sabre\DAV\Exception\Forbidden;
 use Sabre\DAV\Exception\NotFound;
+use Sabre\VObject\InvalidDataException;
 use Test\TestCase;
 
 class CalendarObjectTest extends TestCase {
@@ -216,6 +217,22 @@ public function testPutMapsBadRequestExceptionToBadRequest(): void {
 		$object->put("BEGIN:VCALENDAR\r\nEND:VCALENDAR");
 	}
 
+	public function testPutMapsInvalidDataExceptionToBadRequest(): void {
+		$backend = $this->createMock(DeckCalendarBackend::class);
+		$backend->method('updateCardFromCalendarObject')
+			->willThrowException(new InvalidDataException('Calendar payload must contain exactly one VTODO'));
+
+		$object = new CalendarObject(
+			$this->createCalendarMock(),
+			'card-1.ics',
+			$backend,
+			$this->createCard()
+		);
+
+		$this->expectException(BadRequest::class);
+		$object->put("BEGIN:VCALENDAR\r\nEND:VCALENDAR");
+	}
+
 	public function testPutMapsDoesNotExistExceptionToNotFound(): void {
 		$backend = $this->createMock(DeckCalendarBackend::class);
 		$backend->method('updateCardFromCalendarObject')