Check malloc return value and print error message when fourcc is not supported.

modules/codec/dvbsub.c

@@ -328,7 +328,7 @@ static void Close( vlc_object_t *p_this )
 
     var_Destroy( p_this, DVBSUB_CFG_PREFIX "x" );
     var_Destroy( p_this, DVBSUB_CFG_PREFIX "y" );
-    var_Destroy( p_this, DVBSUB_CFG_PREFIX "position" );    
+    var_Destroy( p_this, DVBSUB_CFG_PREFIX "position" );
 
     free_all( p_dec );
     free( p_sys );
@@ -1788,7 +1788,11 @@ static block_t *Encode( encoder_t *p_enc, subpicture_t *p_subpic )
     if( !p_region ) return NULL;
 
     if( p_region->fmt.i_chroma != VLC_FOURCC('T','E','X','T') &&
-        p_region->fmt.i_chroma != VLC_FOURCC('Y','U','V','P') ) return NULL;
+        p_region->fmt.i_chroma != VLC_FOURCC('Y','U','V','P') )
+    {
+        msg_Err( p_enc, "chroma not supported", p_region->fmt.i_chroma );
+        return NULL;
+    }
 
     if( p_region->fmt.p_palette )
     {