fix: adjust how passed in axios configs are combined with default axios configs in client constructor

src/models/OnspringClient.ts

@@ -63,16 +63,20 @@ export class OnspringClient {
     }
 
     const configDefaults: CreateAxiosDefaults = {
-      baseURL: baseUrl,
       headers: { 'x-apikey': apiKey, 'x-api-version': '2' },
       validateStatus: null,
     };
 
-    // allow user to specify their own config, but
-    // makes sure to override the baseURL, headers,
-    // and validateStatus properties with necessary
-    // default values
-    config = { ...config, ...configDefaults };
+    // always set baseUrl to the value passed to the constructor
+    config.baseURL = baseUrl;
+
+    // merge the config passed to the constructor with the default config
+    // to make sure the necessary api headers are set.
+    config.headers = { ...config.headers, ...configDefaults.headers } as any;
+
+    // only set validateStatus if it is not already set
+    config.validateStatus =
+      config.validateStatus ?? configDefaults.validateStatus;
 
     this._client = axios.create(config);
   }

tests/OnspringClient.spec.ts

@@ -116,6 +116,16 @@ describe('OnspringClient', function () {
     expect(new OnspringClient(baseUrl, apiKey)).to.have.property('_client');
   });
 
+  it('should create a new instance of an onspring client when passed an axios config object', function () {
+    const config = {
+      validateStatus: function (status) {
+        return status >= 200 && status < 300;
+      },
+    };
+
+    expect(() => new OnspringClient(baseUrl, apiKey, config)).to.not.throw();
+  });
+
   describe('canConnect', function () {
     it('should be defined', function () {
       expect(new OnspringClient(baseUrl, apiKey).canConnect).to.not.be