minor #42018 [DomCrawler] Backport type fixes (derrabus)

This PR was merged into the 4.4 branch.

Discussion
----------

[DomCrawler] Backport type fixes

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | N/A
| License       | MIT
| Doc PR        | N/A

Discovered while working on #41981.

Commits
-------

6996988fe5 [DomCrawler] Backport type fixes

src/Symfony/Component/DomCrawler/AbstractUriElement.php

@@ -35,7 +35,7 @@ abstract class AbstractUriElement
 
     /**
      * @param \DOMElement $node       A \DOMElement instance
-     * @param string      $currentUri The URI of the page where the link is embedded (or the base href)
+     * @param string|null $currentUri The URI of the page where the link is embedded (or the base href)
      * @param string|null $method     The method to use for the link (GET by default)
      *
      * @throws \InvalidArgumentException if the node is not a link

src/Symfony/Component/DomCrawler/Crawler.php

@@ -21,20 +21,29 @@ use Symfony\Component\CssSelector\CssSelectorConverter;
  */
 class Crawler implements \Countable, \IteratorAggregate
 {
+    /**
+     * @var string|null
+     */
     protected $uri;
 
     /**
-     * @var string The default namespace prefix to be used with XPath and CSS expressions
+     * The default namespace prefix to be used with XPath and CSS expressions.
+     *
+     * @var string
      */
     private $defaultNamespacePrefix = 'default';
 
     /**
-     * @var array A map of manually registered namespaces
+     * A map of manually registered namespaces.
+     *
+     * @var array<string, string>
      */
     private $namespaces = [];
 
     /**
-     * @var string The base href value
+     * The base href value.
+     *
+     * @var string|null
      */
     private $baseHref;
 
@@ -75,7 +84,7 @@ class Crawler implements \Countable, \IteratorAggregate
     /**
      * Returns the current URI.
      *
-     * @return string
+     * @return string|null
      */
     public function getUri()
     {
@@ -85,7 +94,7 @@ class Crawler implements \Countable, \IteratorAggregate
     /**
      * Returns base href.
      *
-     * @return string
+     * @return string|null
      */
     public function getBaseHref()
     {

src/Symfony/Component/DomCrawler/Form.php

@@ -38,9 +38,9 @@ class Form extends Link implements \ArrayAccess
 
     /**
      * @param \DOMElement $node       A \DOMElement instance
-     * @param string      $currentUri The URI of the page where the form is embedded
-     * @param string      $method     The method to use for the link (if null, it defaults to the method defined by the form)
-     * @param string      $baseHref   The URI of the <base> used for relative links, but not for empty action
+     * @param string|null $currentUri The URI of the page where the form is embedded
+     * @param string|null $method     The method to use for the link (if null, it defaults to the method defined by the form)
+     * @param string|null $baseHref   The URI of the <base> used for relative links, but not for empty action
      *
      * @throws \LogicException if the node is not a button inside a form tag
      */