bug symfony#28592 [BrowserKit] throw exception when request() wasn't called (xabbuh)

This PR was merged into the 4.2-dev branch.

Discussion
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[BrowserKit] throw exception when request() wasn't called

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony#27807 (comment)

Commits
-------

41cfde1 throw exception when request() wasn't called

Author: nicolas-grekas

src/Symfony/Component/BrowserKit/Client.php

@@ -297,7 +297,11 @@ public function click(Link $link)
      */
     public function clickLink(string $linkText): Crawler
     {
-        return $this->click($this->getCrawler()->selectLink($linkText)->link());
+        if (null === $this->crawler) {
+            throw new BadMethodCallException(sprintf('The "request()" method must be called before "%s()".', __METHOD__));
+        }
+
+        return $this->click($this->crawler->selectLink($linkText)->link());
     }
 
     /**
@@ -332,7 +336,11 @@ public function submit(Form $form, array $values = array()/*, array $serverParam
      */
     public function submitForm(string $button, array $fieldValues = array(), string $method = 'POST', array $serverParameters = array()): Crawler
     {
-        $buttonNode = $this->getCrawler()->selectButton($button);
+        if (null === $this->crawler) {
+            throw new BadMethodCallException(sprintf('The "request()" method must be called before "%s()".', __METHOD__));
+        }
+
+        $buttonNode = $this->crawler->selectButton($button);
         $form = $buttonNode->form($fieldValues, $method);
 
         return $this->submit($form, array(), $serverParameters);