Pass http.ServeTLS() errors back to the caller

Closes: #2460

rpc/lib/server/http_server.go

@@ -102,15 +102,16 @@ func StartHTTPAndTLSServer(
 		listener = netutil.LimitListener(listener, config.MaxOpenConnections)
 	}
 
-	go func() {
-		err := http.ServeTLS(
-			listener,
-			RecoverAndLogHandler(maxBytesHandler{h: handler, n: maxBodyBytes}, logger),
-			certFile,
-			keyFile,
-		)
+	err = http.ServeTLS(
+		listener,
+		RecoverAndLogHandler(maxBytesHandler{h: handler, n: maxBodyBytes}, logger),
+		certFile,
+		keyFile,
+	)
+	if err != nil {
 		logger.Error("RPC HTTPS server stopped", "err", err)
-	}()
+		return nil, err
+	}
 	return listener, nil
 }
 

rpc/lib/server/http_server_test.go

@@ -5,11 +5,14 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"os"
 	"sync"
 	"sync/atomic"
 	"testing"
 	"time"
 
+	"github.com/stretchr/testify/require"
+
 	"github.com/tendermint/tendermint/libs/log"
 )
 
@@ -60,3 +63,15 @@ func TestMaxOpenConnections(t *testing.T) {
 		t.Errorf("%d requests failed within %d attempts", failed, attempts)
 	}
 }
+
+func TestStartHTTPAndTLSServer(t *testing.T) {
+	// set up fixtures
+	listenerAddr := "tcp://0.0.0.0:0"
+	mux := http.NewServeMux()
+	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {})
+
+	// test failure
+	gotListener, err := StartHTTPAndTLSServer(listenerAddr, mux, "", "", log.TestingLogger(), Config{MaxOpenConnections: 1})
+	require.Nil(t, gotListener)
+	require.IsType(t, (*os.PathError)(nil), err)
+}