refactor(types): add checks

src/internal/common.h

@@ -23,7 +23,7 @@ struct memory_buffer {
 typedef struct tgbot {
 	char token[TOKEN_SIZE]; /**< Bot token. */
 	char api[API_SIZE];		/**< Bot API url. */
-	int32_t offset;			/**< Bot offset. */
+	int64_t offset;			/**< Bot offset. */
 } tgbot_s;
 
 enum tgbot_opt_type {

src/types.c

@@ -29,6 +29,10 @@ void tgbot_inlinekb_free(tgbot_inlinekeyboard_s *keyboard) {
 }
 
 tgbot_inlinekeyboardbutton_s *tgbot_inlinekb_button_at(tgbot_inlinekeyboard_s *keyboard, size_t row, size_t column) {
+	if (row >= keyboard->rows || column >= keyboard->columns) {
+		return NULL;
+	}
+
 	return &keyboard->buttons[row * keyboard->columns + column];
 }