Handle chained function call expressions

Upsilon/Binder/Binder.cs

@@ -335,6 +335,12 @@ namespace Upsilon.Binder
                     return new VariableSymbol(fullStopIndexExpression.Index, Type.Unknown, true);
                 }
             }
+
+            if (expression.Kind == BoundKind.BoundFunctionCallExpression)
+            {
+                return new VariableSymbol("", expression.Type, true);
+            }
+            _diagnostics.LogError("Can't resolve variable", expression.Span);
             return null;
         }