fix: fix URL builder issues

* basepath normalization: String.replace is not in-place.
* params: unshift adds array items, we wanted to pop the last item.

src/store/api-helper.js

@@ -90,12 +90,12 @@ export function callOrReturn(response, callback) {
 function createURLBuilder(basepath, useTrailingSlash = true) {
   // Strip all trailing slashes from the basepath.
   // We handle slashes when building URLs.
-  basepath.replace(/\/*$/, '')
+  basepath = basepath.replace(/\/*$/, '')
 
   return function buildURL(...subPaths) {
     let params
     if (subPaths.at(-1) instanceof URLSearchParams) {
-      params = subPaths.unshift()
+      params = subPaths.pop()
     }
     if (subPaths.some((path) => String(path).includes('/'))) {
       throw new Error('Subpaths must not contain slashes')