minor #30740 [HttpClient] Remove unused local variable (samnela)

This PR was merged into the 4.3-dev branch.

Discussion
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[HttpClient] Remove unused local variable

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Commits
-------

60b077337c [HttpClient] Remove unused local variable

src/Symfony/Component/HttpClient/Chunk/ErrorChunk.php

@@ -28,7 +28,6 @@ class ErrorChunk implements ChunkInterface
 
     public function __construct(int $offset, \Throwable $error = null)
     {
-        $didThrow = false;
         $this->offset = $offset;
         $this->error = $error;
         $this->errorMessage = null !== $error ? $error->getMessage() : 'Reading from the response stream reached the inactivity timeout.';