bug #35137 [Messenger] Added check if json_encode succeeded (toooni)

This PR was submitted for the master branch but it was squashed and merged into the 4.4 branch instead (closes #35137).

Discussion
----------

[Messenger] Added check if json_encode succeeded

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

When trying to add a message to redis transport which can not be encoded with `json_encode` there is now a `TransportException` containing the `json_last_error_msg` as the message.
I had an issue where I tried to send an email through messenger by symfony mailer which contains a pdf attachment. Instead of an error while sending i got an error `Encoded envelope should have at least a "body"` which happened because the encoded message was `false`.

This is not exactly a bugfix, but IMO also not a feature worth being mentioned in the changelog so I am not sure I've filled out the Q/A correctly.

Commits
-------

a16a574 [Messenger] Added check if json_encode succeeded

src/Symfony/Component/Messenger/Tests/Transport/RedisExt/ConnectionTest.php

@@ -186,6 +186,20 @@ public function testGetNonBlocking()
         $redis->del('messenger-getnonblocking');
     }
 
+    public function testJsonError()
+    {
+        $redis = new \Redis();
+
+        $connection = Connection::fromDsn('redis://localhost/json-error', [], $redis);
+
+        try {
+            $connection->add("\xB1\x31", []);
+        } catch (TransportException $e) {
+        }
+
+        $this->assertSame('Malformed UTF-8 characters, possibly incorrectly encoded', $e->getMessage());
+    }
+
     public function testMaxEntries()
     {
         $redis = $this->getMockBuilder(\Redis::class)->disableOriginalConstructor()->getMock();

src/Symfony/Component/Messenger/Transport/RedisExt/Connection.php

@@ -248,6 +248,10 @@ public function add(string $body, array $headers, int $delayInMs = 0): void
                     'uniqid' => uniqid('', true),
                 ]);
 
+                if (false === $message) {
+                    throw new TransportException(json_last_error_msg());
+                }
+
                 $score = (int) ($this->getCurrentTimeInMilliseconds() + $delayInMs);
                 $added = $this->connection->zadd($this->queue, ['NX'], $score, $message);
             } else {
@@ -256,6 +260,10 @@ public function add(string $body, array $headers, int $delayInMs = 0): void
                     'headers' => $headers,
                 ]);
 
+                if (false === $message) {
+                    throw new TransportException(json_last_error_msg());
+                }
+
                 if ($this->maxEntries) {
                     $added = $this->connection->xadd($this->stream, '*', ['message' => $message], $this->maxEntries, true);
                 } else {