Do not delete keys file if no entries are found

This is follow-up to #3545

It's assumed that if user drops keys file into ASF's config directory, their intention is to make use of that file in order to add something into ASF. While we filter it out and accept the fact that the file may not represent 1:1 ASF's required input, there should be at least one valid entry to assume that user knows what they're doing.

Therefore, deleting the file outright is probably not a good idea, now that we have logging, it's better to leave file as-is and allow user to correct it. Of course, one could also argue that such correction is impossible if 1+ valid entries are found, but that's no longer our concern, user is expected to drop valid file there to begin with, and we're only adding logic for the most obvious kind of mistake, not all mistakes possible.

Author: JustArchi

ArchiSteamFarm/Steam/Bot.cs

@@ -1490,18 +1490,22 @@ internal async Task ImportKeysToRedeem(string filePath) {
 				}
 			}
 
-			if (gamesToRedeemInBackground.Count > 0) {
-				FilterGamesToRedeemInBackground(gamesToRedeemInBackground);
-
-				if (gamesToRedeemInBackground.Count > 0) {
-					AddGamesToRedeemInBackground(gamesToRedeemInBackground);
-				} else {
-					ArchiLogger.LogGenericWarning(Strings.WarningNoValidKeysFound);
-				}
-			} else {
+			if (gamesToRedeemInBackground.Count == 0) {
 				ArchiLogger.LogGenericError(Strings.FormatErrorIsEmpty(filePath));
+
+				return;
 			}
 
+			FilterGamesToRedeemInBackground(gamesToRedeemInBackground);
+
+			if (gamesToRedeemInBackground.Count == 0) {
+				ArchiLogger.LogGenericWarning(Strings.WarningNoValidKeysFound);
+
+				return;
+			}
+
+			AddGamesToRedeemInBackground(gamesToRedeemInBackground);
+
 			File.Delete(filePath);
 		} catch (Exception e) {
 			ArchiLogger.LogGenericException(e);