gh-112388: Fix an error that was causing the parser to try to overwrite tokenizer errors (#112410)

Signed-off-by: Pablo Galindo <pablogsal@gmail.com>

Author: pablogsal

Lib/test/test_syntax.py

@@ -2349,6 +2349,7 @@ def test_error_string_literal(self):
 
     def test_invisible_characters(self):
         self._check_error('print\x17("Hello")', "invalid non-printable character")
+        self._check_error(b"with(0,,):\n\x01", "invalid non-printable character")
 
     def test_match_call_does_not_raise_syntax_error(self):
         code = """

Misc/NEWS.d/next/Core and Builtins/2023-11-25-22-58-49.gh-issue-112388.MU3cIM.rst

@@ -0,0 +1,2 @@
+Fix an error that was causing the parser to try to overwrite tokenizer
+errors. Patch by pablo Galindo

Parser/pegen_errors.c

@@ -219,6 +219,10 @@ _PyPegen_tokenize_full_source_to_check_for_errors(Parser *p) {
 void *
 _PyPegen_raise_error(Parser *p, PyObject *errtype, int use_mark, const char *errmsg, ...)
 {
+    // Bail out if we already have an error set.
+    if (p->error_indicator && PyErr_Occurred()) {
+        return NULL;
+    }
     if (p->fill == 0) {
         va_list va;
         va_start(va, errmsg);