fix segfault

[xbeastx]

After build self.emit_logs() has no output and cause some segfault

[Protryon]

How does it having no output cause an error, yet alone a segfault? I'm not seeing this @xbeastx. I triple checked NVIDIA docs, there is no overrun allowed for trailing NUL appending from libcuda. That said, it doesn't state whether or not it even does append nulls, but it never backtracks and does append NULs in practice (as there statement about NUL overrun implies).

Even if no NUL was appended, this would still not segfault or error, just print garbage.