Change exception message to be clearer

Author: dati18

app/Helper/MWTimestampHelper.php

@@ -18,11 +18,11 @@ public static function getCarbonFromMWTimestamp(string $MWTimestamp): CarbonImmu
         try {
             $carbon = CarbonImmutable::createFromFormat(self::MWTimestampFormat, $MWTimestamp);
         } catch (InvalidFormatException $exception) {
-            throw new InvalidFormatException('Unable to create Carbon object', 0, $exception);
+            throw new InvalidFormatException('Unable to create Carbon object: invalid MW timestamp format', 0, $exception);
         }
 
         if (!$carbon instanceof CarbonImmutable) {
-            throw new InvalidFormatException('Unable to create Carbon object');
+            throw new InvalidFormatException('Unable to create Carbon object: parser did not return CarbonImmutable');
         }
 
         return $carbon;

tests/Helper/MWTimestampHelperTest.php

@@ -19,7 +19,7 @@ public function testGetCarbonFromMWTimestamp() {
 
     public function testGetCarbonFromMWTimestampWithInvalidTimestamp() {
         $this->expectException(InvalidFormatException::class);
-        $this->expectExceptionMessage('Unable to create Carbon object');
+        $this->expectExceptionMessage('Unable to create Carbon object: invalid MW timestamp format');
 
         $invalidMwTimestamp = 'invalid_timestamp';
         MWTimestampHelper::getCarbonFromMWTimestamp($invalidMwTimestamp);