Fix null ref from exceptions without a message/reason

Author: borigas

src/CouchDB.Driver/Helpers/RequestsHelper.cs

@@ -23,33 +23,24 @@ public static async Task<T> SendRequestAsync<T>(this Task<T> asyncRequest)
             }
             catch (FlurlHttpException ex)
             {
-                CouchError couchError;
-                try
-                {
-                    couchError = await ex.GetResponseJsonAsync<CouchError>().ConfigureAwait(false);
-                }
-                catch
+                CouchError couchError = await ex.GetResponseJsonAsync<CouchError>().ConfigureAwait(false);
+
+                if (couchError == null)
                 {
-                    throw;
+                    couchError = new CouchError();
                 }
 
-                if (couchError != null)
+                switch (ex.Call.HttpStatus)
                 {
-                    switch (ex.Call.HttpStatus)
-                    {
-                        case HttpStatusCode.Conflict:
-                            throw couchError.NewCouchExteption(typeof(CouchConflictException));
-                        case HttpStatusCode.NotFound:
-                            throw couchError.NewCouchExteption(typeof(CouchNotFoundException));
-                        case HttpStatusCode.BadRequest:
-                            if (couchError.Error == "no_usable_index")
-                            {
-                                throw couchError.NewCouchExteption(typeof(CouchNoIndexException));
-                            }
-                            break;
-                    }
+                    case HttpStatusCode.Conflict:
+                        throw couchError.NewCouchExteption(typeof(CouchConflictException));
+                    case HttpStatusCode.NotFound:
+                        throw couchError.NewCouchExteption(typeof(CouchNotFoundException));
+                    case HttpStatusCode.BadRequest when couchError.Error == "no_usable_index":
+                        throw couchError.NewCouchExteption(typeof(CouchNoIndexException));
+                    default:
+                        throw new CouchException(couchError.Error, couchError.Reason);
                 }
-                throw new CouchException(couchError.Error, couchError.Reason);                
             }
         }