Fix rtaudio crash when there are no system input ports

Signed-off-by: falkTX <falktx@falktx.com>

source/modules/rtaudio/RtAudio.cpp

@@ -2079,20 +2079,20 @@ bool RtApiJack :: probeDeviceOpen( unsigned int device, StreamMode mode, unsigne
   stream_.sampleRate = jackbridge_get_sample_rate( client );
 
   // Get the latency of the JACK port.
-  const char **ports;
-  ports = jackbridge_get_ports( client, "system:", NULL, JackPortIsInput );
-  if ( ports[ firstChannel ] ) {
-    // Added by Ge Wang
-    jack_latency_callback_mode_t cbmode = (mode == INPUT ? JackCaptureLatency : JackPlaybackLatency);
-    // the range (usually the min and max are equal)
-    jack_latency_range_t latrange; latrange.min = latrange.max = 0;
-    // get the latency range
-    jackbridge_port_get_latency_range( jackbridge_port_by_name( client, ports[firstChannel] ), cbmode, &latrange );
-    // be optimistic, use the min!
-    stream_.latency[mode] = latrange.min;
-    //stream_.latency[mode] = jack_port_get_latency( jackbridge_port_by_name( client, ports[ firstChannel ] ) );
-  }
-  jackbridge_free( ports );
+  if (const char **ports = jackbridge_get_ports( client, "system:", NULL, JackPortIsInput )) {
+    if ( ports[ firstChannel ] ) {
+      // Added by Ge Wang
+      jack_latency_callback_mode_t cbmode = (mode == INPUT ? JackCaptureLatency : JackPlaybackLatency);
+      // the range (usually the min and max are equal)
+      jack_latency_range_t latrange; latrange.min = latrange.max = 0;
+      // get the latency range
+      jackbridge_port_get_latency_range( jackbridge_port_by_name( client, ports[firstChannel] ), cbmode, &latrange );
+      // be optimistic, use the min!
+      stream_.latency[mode] = latrange.min;
+      //stream_.latency[mode] = jack_port_get_latency( jackbridge_port_by_name( client, ports[ firstChannel ] ) );
+    }
+    jackbridge_free( ports );
+  }
 
   // The jack server always uses 32-bit floating-point data.
   stream_.deviceFormat[mode] = RTAUDIO_FLOAT32;