Fix TrailingCommaMultiLine when there is no elements (#326)

src/Rules/Punctuation/TrailingCommaMultiLineRule.php

@@ -52,7 +52,13 @@ protected function process(int $tokenIndex, Tokens $tokens): void
             return;
         }
 
-        $isMatchingComma = $tokens->get($previous)->isMatching(Token::PUNCTUATION_TYPE, ',');
+        $previousToken = $tokens->get($previous);
+        if ($previousToken === $token->getRelatedToken()) {
+            // There is no element, so adding a trailing comma will break the code.
+            return;
+        }
+
+        $isMatchingComma = $previousToken->isMatching(Token::PUNCTUATION_TYPE, ',');
         if ($this->useTrailingComma === $isMatchingComma) {
             return;
         }

tests/Rules/Punctuation/TrailingCommaMultiLine/TrailingCommaMultiLineRuleTest.fixed.twig

@@ -40,3 +40,10 @@
     1
     + 2
 ) }}
+
+{% set emptyArray = [
+] %}
+{% set emptyObject = {
+} %}
+{{ emptyCall(
+) }}

tests/Rules/Punctuation/TrailingCommaMultiLine/TrailingCommaMultiLineRuleTest.fixed2.twig

@@ -40,3 +40,10 @@
     1
     + 2
 ) }}
+
+{% set emptyArray = [
+] %}
+{% set emptyObject = {
+} %}
+{{ emptyCall(
+) }}

tests/Rules/Punctuation/TrailingCommaMultiLine/TrailingCommaMultiLineRuleTest.twig

@@ -40,3 +40,10 @@
     1
     + 2
 ) }}
+
+{% set emptyArray = [
+] %}
+{% set emptyObject = {
+} %}
+{{ emptyCall(
+) }}