remove wrong syntax check from parser

Author: PhilippImhof

classes/local/parser.php

@@ -364,17 +364,6 @@ private function parse_general_expression(?int $stopat = null): expression {
                 $this->die(get_string('error_invalidrangesep', 'qtype_formulas'), $nexttoken);
             }
 
-            // We do not allow to a closing paren immediately after an opening paren of the same type.
-            $openingparen = ($type & token::ANY_OPENING_PAREN);
-            $nextclosing = ($nexttype & token::ANY_CLOSING_PAREN);
-            if ($openingparen && $nextclosing) {
-                $a = (object)[
-                    'open' => $value,
-                    'close' => $nextvalue,
-                ];
-                $this->die(get_string('error_emptyparens', 'qtype_formulas', $a), $nexttoken);
-            }
-
             // If we're one token away from the end of the statement, we just read and discard the end-of-statement marker.
             if ($nexttype === token::END_OF_STATEMENT || $nexttype === token::END_GROUP) {
                 $this->read_next();