samplesAvailableSync method
Synchronously checks how many samples are available in the inlet's buffer.
Direct mode only - throws LSLException if useIsolates: true.
This provides maximum timing precision by eliminating all async overhead.
Returns: Number of samples available in the inlet's buffer, if the OS
supports it, otherwise, 1 if there is at least one sample available,
or 0 if no samples are available.
Implementation
int samplesAvailableSync() =>
    requireDirect(() => lsl_samples_available(_inletBang));