PostScriptFunction::parseCode: Fix memory leak on malformed files

Fixes oss-fuzz/8859
diff --git a/poppler/Function.cc b/poppler/Function.cc
index 71992d9..cc32414 100644
--- a/poppler/Function.cc
+++ b/poppler/Function.cc
@@ -1303,6 +1303,7 @@
       if (!tok->cmp("{")) {
 	elsePtr = *codePtr;
 	if (!parseCode(str, codePtr)) {
+	  delete tok;
 	  return gFalse;
 	}
 	delete tok;