LoginPacket: Cater for more error cases

This now doesn't crash unexpectedly at the first sign of broken data.

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "cdf1ae08bd2f3e13b0a766a835ed8cb8",
+    "content-hash": "a011d12545207848fb8fe0fccb1cf18c",
     "packages": [
         {
             "name": "adhocore/json-comment",
@@ -231,6 +231,68 @@
             ],
             "time": "2018-12-03T18:17:01+00:00"
         },
+        {
+            "name": "particle/validator",
+            "version": "v2.3.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/particle-php/Validator.git",
+                "reference": "becaa89160fe220ebd9e9cd10addc62cf2adf3f0"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/particle-php/Validator/zipball/becaa89160fe220ebd9e9cd10addc62cf2adf3f0",
+                "reference": "becaa89160fe220ebd9e9cd10addc62cf2adf3f0",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.4"
+            },
+            "require-dev": {
+                "byrokrat/checkdigit": "^1.0",
+                "giggsey/libphonenumber-for-php": "^7.2",
+                "phpunit/phpunit": "~4.0",
+                "squizlabs/php_codesniffer": "2.*"
+            },
+            "suggest": {
+                "byrokrat/checkdigit": "If you want to use CreditCard validation rule, this library must be installed.",
+                "giggsey/libphonenumber-for-php": "If you want to use Phone validation rule, this library must be installed."
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.0-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Particle\\Validator\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Berry Langerak",
+                    "email": "berry@berryllium.nl",
+                    "role": "developer"
+                },
+                {
+                    "name": "Rick van der Staaij",
+                    "homepage": "http://rickvanderstaaij.nl",
+                    "role": "Developer"
+                }
+            ],
+            "description": "Flexible and highly usable validation library with no dependencies.",
+            "homepage": "http://github.com/particle-php/validator",
+            "keywords": [
+                "validation",
+                "validator"
+            ],
+            "time": "2018-09-12T08:03:23+00:00"
+        },
         {
             "name": "pocketmine/binaryutils",
             "version": "0.1.5",