```
common/test/run-splice_script.c: In function ‘main’:
common/test/run-splice_script.c:349:17: error: ‘%.*s’ directive argument is null [-Werror=format-overflow=]
349 | printf("%.*s\n", (int)len, str);
| ^~~~
cc1: all warnings being treated as errors
make: *** [Makefile:297: common/test/run-splice_script.o] Error 1
make: *** Waiting for unfinished jobs....
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>