[banshee] Dap.MassStorage: discard devices with null MountPoint (bgo#751746)

[Andrés Aragoneses <aaragoneses src gnome org>]

commit 2880a6e0a06521af6b30351b3f6131a7538ecc92
Author: Andrés G. Aragoneses <knocte gmail com>
Date:   Tue Jun 30 21:45:19 2015 +0200

    Dap.MassStorage: discard devices with null MountPoint (bgo#751746)
    
    They simply don't work and would start throwing exceptions later.

 .../Banshee.Dap.MassStorage/MassStorageSource.cs   |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/src/Dap/Banshee.Dap.MassStorage/Banshee.Dap.MassStorage/MassStorageSource.cs 
b/src/Dap/Banshee.Dap.MassStorage/Banshee.Dap.MassStorage/MassStorageSource.cs
index cdf6d38..9f708ed 100644
--- a/src/Dap/Banshee.Dap.MassStorage/Banshee.Dap.MassStorage/MassStorageSource.cs
+++ b/src/Dap/Banshee.Dap.MassStorage/Banshee.Dap.MassStorage/MassStorageSource.cs
@@ -74,6 +74,11 @@ namespace Banshee.Dap.MassStorage
                 volume.Mount ();
             }
 
+            mount_point = volume.MountPoint;
+            if (mount_point == null) {
+                throw new InvalidDeviceException ();
+            }
+
             ms_device = DeviceMapper.Map (this);
             try {
                 if (ms_device.ShouldIgnoreDevice () || !ms_device.LoadDeviceConfiguration ()) {
@@ -103,8 +108,6 @@ namespace Banshee.Dap.MassStorage
             }
 
             Name = ms_device == null ? volume.Name : ms_device.Name;
-            mount_point = volume.MountPoint;
-
             Initialize ();
 
             if (ms_device != null) {