Fix zero-length gnu_printf format string warning

[saghul]

src/quickjs/quickjs.c: In function ‘JS_ReadString’:
src/quickjs/quickjs.c:34274:26: warning: zero-length gnu_printf format string [-Wformat-zero-length]
34274 |         bc_read_trace(s, "");  // hex dump and indentation
      |                          ^~
src/quickjs/quickjs.c: In function ‘JS_ReadFunctionBytecode’:
src/quickjs/quickjs.c:34334:30: warning: zero-length gnu_printf format string [-Wformat-zero-length]
34334 |             bc_read_trace(s, "");   // hex dump + indent

Ref: #502

[bnoordhuis]

That one has been annoying me for some days now :-)

[chqrlie]

That one has been annoying me for some days now :-)

Agreed. How does this patch fix the problem?

[saghul]

That one has been annoying me for some days now :-)

Agreed. How does this patch fix the problem?

Rather than passing an empty string we pass NULL which is OK. When the filename is NULL we seemingly create an atom for the empty string. One could algue that is not right, but I worry of the breakage if we make that change.