gh-149277: Fix error position for invalid numeric literals

Author: anuj-bharambe2004

Misc/NEWS.d/next/Core_and_Builtins/2026-05-06-18-16-33.gh-issue-149277.4uVfSK.rst

@@ -0,0 +1,2 @@
+Fix the :exec:`SyntaxError` caret position for invalid numeric literals to
+point at the first invalid character instead of the last valid one.

Parser/lexer/lexer.c

@@ -352,7 +352,6 @@ verify_end_of_number(struct tok_state *tok, int c, const char *kind) {
     }
     else /* In future releases, only error will remain. */
     if (c < 128 && is_potential_identifier_char(c)) {
-        tok_backup(tok, c);
         _PyTokenizer_syntaxerror(tok, "invalid %s literal", kind);
         return 0;
     }