c# - Binding generic ObservableCollection to ItemsSource of Listview, kills XAML Designer and Visual Studio -

when app launches, i'm setting datacontext of window such:

    <window.datacontext>     <vm:defaultviewmodel />     </window.datacontext> 

then bind observablecollection listview later on with:

<listview margin="10"           minheight="0"           borderthickness="0"           itemssource="{binding clients}">                 <listview.view>                     <gridview>                         <gridviewcolumn header="client id" width="85" displaymemberbinding="{binding clientid}"/>                         <gridviewcolumn header="client name" width="220" displaymemberbinding="{binding clientname}"/>                         <gridviewcolumn header="branch" width="60" displaymemberbinding="{binding branch}" />                         <gridviewcolumn header="client number" width="125" displaymemberbinding="{binding clientnumber}"/>                         <gridviewcolumn header="fed id" width="75" displaymemberbinding="{binding fedid}"/>                         <gridviewcolumn header="account manager" width="155" displaymemberbinding="{binding accountmanager}"/>                         <gridviewcolumn header="region" width="61" displaymemberbinding="{binding region}"/>                     </gridview>                 </listview.view> </listview> 

that client list queried upon startup , set in default view model's constructor. problem application doesn't launch - client list bound , visible in xaml designer! , brings visual studio halt in general. what's issue here?

edit: here how data being bound (getclients runs query populates results observablecollection) -

public class defaultviewmodel : inotifypropertychanged {     public defaultviewmodel()     {         _clients = datasource.getclients();     }      private observablecollection<client> _clients;     public observablecollection<client> clients     {         { return _clients; }         set { set(ref _clients, value); }     }       public void raisepropertychanged([callermembername]string propertyname = null)     {         propertychanged?.invoke(this, new propertychangedeventargs(propertyname));     }      public bool set<t>(ref t storage, t value, [callermembername]string propertyname = null)     {         if (equals(storage, value))             return false;         storage = value;         raisepropertychanged(propertyname);         return true;     }      public event propertychangedeventhandler propertychanged; } 

and here getclients function:

        public static observablecollection<client> getclients()     {         var clients = new observablecollection<client>();         var query = file.readalltext(@"file_path");          using (var cn = new oledbconnection(pia_connection_string))         {             var cmd = new oledbcommand(query, cn);             cn.open();              using (var reader = cmd.executereader())             {                 while (reader.read())                 {                     var client = new client                     {                         clientid = int.parse(reader[0].tostring())                     };                     clients.add(client);                 }             }         }          return clients;     }