handle after != null && limit == null case

app/src/main/java/com/futo/polycentric/core/ApiMethods.kt

@@ -84,6 +84,8 @@ class ApiMethods {
                 "/query_index?system=$systemQuery&content_type=$contentType&after=$after&limit=$limit"
             } else if (limit != null) {
                 "/query_index?system=$systemQuery&content_type=$contentType&limit=$limit"
+            } else if (after != null) {
+                "/query_index?system=$systemQuery&content_type=$contentType&after=$after"
             } else {
                 "/query_index?system=$systemQuery&content_type=$contentType"
             }