fix: few bugs with error shadowing (#1737)

Signed-off-by: Maksim An <maksiman@microsoft.com>

internal/guest/runtime/hcsv2/uvm.go

@@ -543,7 +543,8 @@ func (h *Host) modifyHostSettings(ctx context.Context, containerID string, req *
 	case guestresource.ResourceTypeMappedVirtualDisk:
 		mvd := req.Settings.(*guestresource.LCOWMappedVirtualDisk)
 		// find the actual controller number on the bus and update the incoming request.
-		cNum, err := scsi.ActualControllerNumber(ctx, mvd.Controller)
+		var cNum uint8
+		cNum, err = scsi.ActualControllerNumber(ctx, mvd.Controller)
 		if err != nil {
 			return err
 		}
@@ -552,7 +553,8 @@ func (h *Host) modifyHostSettings(ctx context.Context, containerID string, req *
 		if !mvd.ReadOnly {
 			localCtx, cancel := context.WithTimeout(ctx, time.Second*5)
 			defer cancel()
-			source, err := scsi.ControllerLunToName(localCtx, mvd.Controller, mvd.Lun)
+			var source string
+			source, err = scsi.ControllerLunToName(localCtx, mvd.Controller, mvd.Lun)
 			if err != nil {
 				return err
 			}

internal/uvm/create_lcow.go

@@ -610,14 +610,14 @@ func makeLCOWDoc(ctx context.Context, opts *OptionsLCOW, uvm *UtilityVM) (_ *hcs
 				pmem := newPackedVPMemDevice()
 				pmem.maxMappedDeviceCount = 1
 
-				st, err := os.Stat(rootfsFullPath)
-				if err != nil {
-					return nil, errors.Wrapf(err, "failed to stat rootfs: %q", rootfsFullPath)
+				st, stErr := os.Stat(rootfsFullPath)
+				if stErr != nil {
+					return nil, errors.Wrapf(stErr, "failed to stat rootfs: %q", rootfsFullPath)
 				}
 				devSize := pageAlign(uint64(st.Size()))
-				memReg, err := pmem.Allocate(devSize)
-				if err != nil {
-					return nil, errors.Wrap(err, "failed to allocate memory for rootfs")
+				memReg, pErr := pmem.Allocate(devSize)
+				if pErr != nil {
+					return nil, errors.Wrap(pErr, "failed to allocate memory for rootfs")
 				}
 				defer func() {
 					if err != nil {