feat: enhance logging for proxy testing errors

This commit improves the logging in the testProxy method of the
ProxyController class. Now, when an Axios error occurs, the specific
error message will be logged if available. For unexpected errors, the
error object is included for better insight.

For reference, see the "message" field in the Axios documentation:
[Axios Error Handling](https://axios-http.com/docs/handling_errors).

Author: henrybarreto

src/api/controllers/proxy.controller.ts

@@ -53,15 +53,21 @@ export class ProxyController {
         httpsAgent: makeProxyAgent(proxy),
       });
 
-      return response?.data !== serverIp?.data;
+      const result = response?.data !== serverIp?.data;
+      if (result) {
+        logger.info('testProxy: proxy connection successful');
+      } else {
+        logger.warn("testProxy: proxy connection doesn't change the origin IP");
+      }
+
+      return result;
     } catch (error) {
-      if (axios.isAxiosError(error) && error.response?.data) {
-        logger.error('testProxy error: ' + error.response.data);
-      } else if (axios.isAxiosError(error)) {
-        logger.error('testProxy error: ');
+      if (axios.isAxiosError(error)) {
+        logger.error('testProxy error: axios error: ' + error.message);
       } else {
-        logger.error('testProxy error: ');
+        logger.error('testProxy error: unexpected error: ' + error);
       }
+
       return false;
     }
   }