refactor: simplify null coalescing and optional chaining in getOverlapping (#265)

* refactor(IslamicCalendar): simplify null coalescing and optional chaining in getOverlapping

Replaced explicit null check and exception throw with null coalescing + throw expression.
Also added optional chaining to ensure safer date calculation using CarbonImmutable.

* refactor(IndianCalender): simplify null coalescing and optional chaining in getOverlapping

Replaced explicit null check and exception throw with null coalescing + throw expression.
Also added optional chaining to ensure safer date calculation using CarbonImmutable.

---------

Co-authored-by: root <root@localhost>

Author: Ayoub-Mabrouk

src/Calendars/IndianCalender.php

@@ -110,23 +110,15 @@ protected function getOverlapping(array $collection, int $year, int $totalDays):
             return null;
         }
 
-        $date = $collection[$year - 1] ?? null;
-
-        if ($date === null) {
-            throw InvalidYear::range($this->countryCode(), 1970, 2037);
-        }
+        $date = $collection[$year - 1] ?? throw InvalidYear::range($this->countryCode(), 1970, 2037);
 
         if (is_array($date)) {
             $date = end($date);
         }
 
         $start = CarbonImmutable::createFromFormat('Y-m-d', "{$year}-{$date}")?->startOfDay();
-        $end = $start->addDays($totalDays - 1)->startOfDay();
-
-        if ($end->year !== $year) {
-            return (string) $date;
-        }
+        $end = $start?->addDays($totalDays - 1)->startOfDay();
 
-        return null;
+        return ($end?->year !== $year) ? (string) $date : null;
     }
 }

src/Calendars/IslamicCalendar.php

@@ -124,24 +124,16 @@ protected function getOverlapping(array $collection, int $year, int $totalDays):
             return null;
         }
 
-        $date = $collection[$year - 1] ?? null;
-
-        if ($date === null) {
-            throw InvalidYear::range($this->countryCode(), 1970, 2037);
-        }
+        $date = $collection[$year - 1] ?? throw InvalidYear::range($this->countryCode(), 1970, 2037);
 
         if (is_array($date)) {
             $date = end($date);
         }
 
         $start = CarbonImmutable::createFromFormat('Y-m-d', "{$year}-{$date}")?->startOfDay();
-        $end = $start->addDays($totalDays - 1)->startOfDay();
-
-        if ($end->year !== $year) {
-            return (string) $date;
-        }
+        $end = $start?->addDays($totalDays - 1)->startOfDay();
 
-        return null;
+        return ($end?->year !== $year) ? (string) $date : null;
     }
 
     public function setIslamicCalendarTimezone(string $islamicCalendarTimezone): static