fix: minor example tweaks

Signed-off-by: Christopher Arndt <chris@chrisarndt.de>

examples/jacket_port_connect_cb.nim

@@ -42,7 +42,6 @@ proc portConnected(portA: PortIdT; portB: PortIdT; connect: cint; arg: pointer)
         echo "Port B: <unknown>"
         
     echo("Action: ", if connect > 0: "connect" else: "disconnect")
-    
 
 addHandler(log)
 setErrorFunction(errorCb)

examples/jacket_port_register.nim

@@ -33,7 +33,7 @@ debug "JACK server status: " & $status
 
 if jclient == nil:
     error getJackStatusErrorString(status)
-    quit 1
+    quit QuitFailure
 
 when defined(windows):
     setSignalProc(signalCb, SIGABRT, SIGINT, SIGTERM)

examples/jacket_sine.nim

@@ -79,10 +79,10 @@ debug "JACK server status: " & $status
 
 if jclient == nil:
     error getJackStatusErrorString(status)
-    quit 1
+    quit QuitFailure
 
 # Create sine oscillator
-let sampleRate =(float) jclient.getSampleRate()
+let sampleRate = jclient.getSampleRate.float
 debug "JACK sample rate: " & $sampleRate
 var osc = initSineOsc(sampleRate, sineFreq)
 
@@ -96,6 +96,7 @@ else:
 if jclient.setProcessCallback(processCb, osc.addr) != 0:
     error "Could not set JACK process callback function."
     cleanup()
+    quit QuitFailure
 
 jclient.onShutdown(shutdownCb, nil)