Allow disabling player online autosaves (#971)

CHANGELOG.md

@@ -47,6 +47,7 @@ Many thanks to the following for contributing to this release:
 
 ### Fixes
 
+- Allow player online autosave slots to be disabled while autosaves are enabled. [#966](<https://github.com/clusterio/clusterio/issues/966>)
 - Silenced two Ant Design console warnings in the Web UI: the deprecated Modal `destroyOnClose` prop, and a duplicate-value warning from the instance version selector. [#940](<https://github.com/clusterio/clusterio/pull/940>)
 - Surface the mod portal's own error when downloading mods for an unsupported Factorio version. [#941](<https://github.com/clusterio/clusterio/pull/941>)
 - Instances always create their config file on assignment preventing duplicate folder creation. [#945](<https://github.com/clusterio/clusterio/pull/945>)

packages/lib/src/config/definitions.ts

@@ -575,7 +575,7 @@ export class InstanceConfig extends classes.Config<InstanceConfigFields> {
 			validator: function(value, config) {
 				const factorioSettings = config.get("factorio.settings");
 				const autosaveSlots = factorioSettings.autosave_slots;
-				if (typeof autosaveSlots === "number" && value < autosaveSlots) {
+				if (value !== 0 && typeof autosaveSlots === "number" && value < autosaveSlots) {
 					throw new Error("Value cannot be less than the number of autosave slots");
 				}
 			},

test/lib/config/validators.test.js

@@ -227,6 +227,15 @@ describe("lib/config/definitions/validators", function() {
 					/Value cannot be less than the number of autosave slots/
 				);
 			});
+			it("should allow disabling player online autosaves", function() {
+				const config = new InstanceConfig("controller", {
+					"factorio.settings": {
+						autosave_slots: 5,
+					},
+				});
+
+				assert.doesNotThrow(() => config.set("factorio.player_online_autosave_slots", 0));
+			});
 			it("should allow when autosave_slots is not a number", function() {
 				const config = new InstanceConfig("controller", {
 					"factorio.settings": {