Do not require error links object to contain an about member

Author: JaZo

src/Parsers/LinksParser.php

@@ -49,9 +49,6 @@ public function parse($data, string $source): Links
         if (!is_object($data)) {
             throw new ValidationException(sprintf('Links MUST be an object, "%s" given.', gettype($data)));
         }
-        if ($source === self::SOURCE_ERROR && !property_exists($data, 'about')) {
-            throw new ValidationException('Error links object MUST contain at least one of the following properties: `about`.');
-        }
         if ($source === self::SOURCE_RELATIONSHIP && !property_exists($data, 'self') && !property_exists($data, 'related')) {
             throw new ValidationException('Relationship links object MUST contain at least one of the following properties: `self`, `related`.');
         }

tests/Parsers/LinksParserTest.php

@@ -127,19 +127,6 @@ public function it_throws_when_related_link_is_null()
         $parser->parse(json_decode('{"related": null}', false), LinksParser::SOURCE_DOCUMENT);
     }
 
-    /**
-     * @test
-     */
-    public function it_throws_when_error_links_misses_about_link()
-    {
-        $parser = new LinksParser($this->createMock(MetaParser::class));
-
-        $this->expectException(ValidationException::class);
-        $this->expectExceptionMessage('Error links object MUST contain at least one of the following properties: `about`.');
-
-        $parser->parse(json_decode('{}', false), LinksParser::SOURCE_ERROR);
-    }
-
     /**
      * @test
      */