Change error handling

- Catch only standard errors
- Include original error message in raise error

Author: Mooli Tayer

lib/prometheus/api_client/client.rb

@@ -102,8 +102,8 @@ def run_command(command, options)
         response = get(command, options)
 
         JSON.parse(response.body)['data']
-      rescue
-        raise RequestError, 'Bad response from server'
+      rescue StandardError => err
+        raise RequestError, err.message
       end
 
       # Helper function to evalueate the low level proxy option