[FIX] Wait in the main goroutine

Wait in the main routine for the interrupt signal instead of exiting the main routine.
We are facing some crash when we try to gracefuly shoutdown the container.

From the Official Documentation:
Calling Goexit from the main goroutine terminates that goroutine without func main returning.
Since func main has not returned, the program continues execution of other goroutines.
If all other goroutines exit, the program crashes.

https://pkg.go.dev/runtime#Goexit

main.go

@@ -20,8 +20,8 @@ import (
 	"net/url"
 	"os"
 	"os/signal"
-	"runtime"
 	"strings"
+	"syscall"
 	"time"
 
 	"github.com/nats-io/prometheus-nats-exporter/collector"
@@ -92,6 +92,10 @@ func main() {
 	var retryInterval int
 	var printVersion bool
 
+	// Setup the interrupt handler to gracefully exit.
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
+
 	opts := exporter.GetDefaultExporterOptions()
 
 	// Parse flags
@@ -200,14 +204,6 @@ necessary.`)
 		collector.Fatalf("error starting the exporter: %v\n", err)
 	}
 
-	// Setup the interrupt handler to gracefully exit.
-	c := make(chan os.Signal, 1)
-	signal.Notify(c, os.Interrupt)
-	go func() {
-		<-c
-		exp.Stop()
-		os.Exit(0)
-	}()
-
-	runtime.Goexit()
+	<-c
+	exp.Stop()
 }