Backtrace included in InvalidDocblock message

[AndrolGenhald]

https://psalm.dev/r/4d782ddd22

I thought it was a crash at first, but we're actually including a backtrace in the message.

Semi-related to #8322

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/4d782ddd22

<?php
                    namespace Bar;

                    /**
                     * Asserts that two variables are not the same.
                     *
                     * @template T
                     * @param T      $expected
                     * @param mixed  $actual
                     * @psalm-assert !=$expected $actual
                     */
                    function assertNotSame($expected, $actual) : void {}

                    $expected = rand(0, 1) ? 4 : 5;
                    $actual = 6;
                    assertNotSame($expected, $actual);
/** @psalm-trace $actual */;

Psalm output (using commit 4b2935f):

ERROR: InvalidDocblock - 12:21 - Invalid @psalm-assert union type Psalm\Exception\TypeParseTreeException: Invalid type '$expected' in /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/Type/TypeParser.php:384
Stack trace:
#0 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/Type/TypeParser.php(145): Psalm\Internal\Type\TypeParser::getTypeFromTree()
#1 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeDocblockScanner.php(614): Psalm\Internal\Type\TypeParser::parseTokens()
#2 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeDocblockScanner.php(1215): Psalm\Internal\PhpVisitor\Reflector\FunctionLikeDocblockScanner::getAssertionParts()
#3 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeDocblockScanner.php(230): Psalm\Internal\PhpVisitor\Reflector\FunctionLikeDocblockScanner::handleAssertions()
#4 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeNodeScanner.php(517): Psalm\Internal\PhpVisitor\Reflector\FunctionLikeDocblockScanner::addDocblockInfo()
#5 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/PhpVisitor/ReflectorVisitor.php(235): Psalm\Internal\PhpVisitor\Reflector\FunctionLikeNodeScanner->start()
#6 /var/www/vhosts/psalm.dev/httpdocs/vendor/nikic/php-parser/lib/PhpParser/NodeTraverser.php(200): Psalm\Internal\PhpVisitor\ReflectorVisitor->enterNode()
#7 /var/www/vhosts/psalm.dev/httpdocs/vendor/nikic/php-parser/lib/PhpParser/NodeTraverser.php(114): PhpParser\NodeTraverser->traverseArray()
#8 /var/www/vhosts/psalm.dev/httpdocs/vendor/nikic/php-parser/lib/PhpParser/NodeTraverser.php(223): PhpParser\NodeTraverser->traverseNode()
#9 /var/www/vhosts/psalm.dev/httpdocs/vendor/nikic/php-parser/lib/PhpParser/NodeTraverser.php(91): PhpParser\NodeTraverser->traverseArray()
#10 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/Scanner/FileScanner.php(88): PhpParser\NodeTraverser->traverse()
#11 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/Codebase/Scanner.php(581): Psalm\Internal\Scanner\FileScanner->scan()
#12 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/Codebase/Scanner.php(809): Psalm\Internal\Codebase\Scanner->scanFile()
#13 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/Codebase/Scanner.php(451): Psalm\Internal\Codebase\Scanner->scanAPath()
#14 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Internal/Codebase/Scanner.php(304): Psalm\Internal\Codebase\Scanner->scanFilePaths()
#15 /var/www/vhosts/psalm.dev/httpdocs/vendor/vimeo/psalm/src/Psalm/Codebase.php(504): Psalm\Internal\Codebase\Scanner->scanFiles()
#16 /var/www/vhosts/psalm.dev/httpdocs/src/OnlineChecker.php(76): Psalm\Codebase->scanFiles()
#17 /var/www/vhosts/psalm.dev/httpdocs/views/snippet.php(88): PsalmDotOrg\OnlineChecker::getResults()
#18 {main}

INFO: UnusedParam - 12:44 - Param $expected is never referenced in this method

INFO: UnusedParam - 12:55 - Param $actual is never referenced in this method

INFO: Trace - 17:28 - $actual: 6