chore: improve null checks

Signed-off-by: Fawzi Abdulfattah <[email protected]>

Author: iifawzi

src/Statements/KillStatement.php

@@ -12,7 +12,6 @@
 use PhpMyAdmin\SqlParser\TokensList;
 
 use function array_slice;
-use function count;
 use function is_int;
 
 /** KILL [HARD|SOFT]
@@ -119,7 +118,7 @@ public function parse(Parser $parser, TokensList $list): void
                     if ($token->type === Token::TYPE_KEYWORD && $token->value === 'SELECT') {
                         $subList = new TokensList(array_slice($list->tokens, $list->idx - 1));
                         $subParser = new Parser($subList);
-                        if (count($subParser->errors)) {
+                        if ($subParser->errors !== []) {
                             foreach ($subParser->errors as $error) {
                                 $parser->errors[] = $error;
                             }
@@ -158,19 +157,15 @@ public function build()
     {
         $ret = 'KILL';
 
-        if ($this->options && count($this->options->options) > 0) {
+        if ($this->options !== null && $this->options->options !== []) {
             $ret .= ' ' . OptionsArray::build($this->options);
         }
 
         if ($this->IDKeywordUsed) {
             $ret .= ' ID';
         }
 
-        $builtIdentifier = (string) $this->identifier;
-        if ($this->identifier instanceof Statement) {
-            $builtIdentifier = $this->identifier->build();
-        }
-
+        $builtIdentifier = $this->identifier;
         if ($this->parenthesisUsed) {
             $ret .= ' (' . $builtIdentifier . ')';
         } elseif ($this->identifier !== null) {