catch errors when trying to resolve DNS (#841)

src/Icons/Services/IconFetchingService.cs

@@ -292,11 +292,18 @@ namespace Bit.Icons.Services
             }
 
             // Resolve host to make sure it is not an internal/private IP address
+            try
+            {
                 var hostEntry = Dns.GetHostEntry(uri.Host);
                 if (hostEntry?.AddressList.Any(ip => IsInternal(ip)) ?? true)
                 {
                     return null;
                 }
+            }
+            catch
+            {
+                return null;
+            }
 
             using (var message = new HttpRequestMessage())
             {