patch 8.2.3411: Vim9: crash when using base name of import

Problem:    Vim9: crash when using base name of import. (Naohiro Ono)
Solution:   Check the import flags. (closes #8843)
diff --git a/src/errors.h b/src/errors.h
index b4c111d..dd72a74 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -654,3 +654,5 @@
 	INIT(= N_("E1234: legacy must be followed by a command"));
 EXTERN char e_function_reference_is_not_set[]
 	INIT(= N_("E1235: Function reference is not set"));
+EXTERN char e_cannot_use_str_itself_it_is_imported_with_star[]
+	INIT(= N_("E1236: Cannot use %s itself, it is imported with '*'"));