Remove usage of empty function when possible

Author: alamirault

Lexer.php

@@ -54,7 +54,7 @@ public function tokenize(string $expression): TokenStream
                 ++$cursor;
             } elseif (str_contains(')]}', $expression[$cursor])) {
                 // closing bracket
-                if (empty($brackets)) {
+                if (!$brackets) {
                     throw new SyntaxError(sprintf('Unexpected "%s".', $expression[$cursor]), $cursor, $expression);
                 }
 
@@ -97,7 +97,7 @@ public function tokenize(string $expression): TokenStream
 
         $tokens[] = new Token(Token::EOF_TYPE, null, $cursor + 1);
 
-        if (!empty($brackets)) {
+        if ($brackets) {
             [$expect, $cur] = array_pop($brackets);
             throw new SyntaxError(sprintf('Unclosed "%s".', $expect), $cur, $expression);
         }

Parser.php

@@ -404,7 +404,7 @@ public function parseArguments()
         $args = [];
         $this->stream->expect(Token::PUNCTUATION_TYPE, '(', 'A list of arguments must begin with an opening parenthesis');
         while (!$this->stream->current->test(Token::PUNCTUATION_TYPE, ')')) {
-            if (!empty($args)) {
+            if ($args) {
                 $this->stream->expect(Token::PUNCTUATION_TYPE, ',', 'Arguments must be separated by a comma');
             }