[3.10] bpo-45727: Make the syntax error for missing comma more consistent (GH-29427) (GH-29647)

(cherry picked from commit 546cefcda75d7150b55c8bc1724bea35a1e12890)

Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>
diff --git a/Parser/pegen.c b/Parser/pegen.c
index 9bf4fe7..98f07a1 100644
--- a/Parser/pegen.c
+++ b/Parser/pegen.c
@@ -79,7 +79,9 @@
 
 int
 _PyPegen_check_legacy_stmt(Parser *p, expr_ty name) {
-    assert(name->kind == Name_kind);
+    if (name->kind != Name_kind) {
+        return 0;
+    }
     const char* candidates[2] = {"print", "exec"};
     for (int i=0; i<2; i++) {
         if (PyUnicode_CompareWithASCIIString(name->v.Name.id, candidates[i]) == 0) {