Sniff::is_assignment(): minor defensive coding tweak

There "bracket_closer" index may not be set during live coding/in case of parse errors. This prevents the method from throwing "_Undefined index: bracket_closer_" notices in that case.

Author: jrfnl

WordPress/Sniff.php

@@ -1321,7 +1321,9 @@ protected function is_assignment( $stackPtr ) {
 		}
 
 		// Check if this is an array assignment, e.g., `$var['key'] = 'val';` .
-		if ( \T_OPEN_SQUARE_BRACKET === $this->tokens[ $next_non_empty ]['code'] ) {
+		if ( \T_OPEN_SQUARE_BRACKET === $this->tokens[ $next_non_empty ]['code']
+			&& isset( $this->tokens[ $next_non_empty ]['bracket_closer'] )
+		) {
 			return $this->is_assignment( $this->tokens[ $next_non_empty ]['bracket_closer'] );
 		}