Fix setting initial window size causes crash at startup, #5250 (#5259)

This commit will:
- Add an enableAllMenus method to MenuController
- Add a disableMenus parameter to Utility.showAlert
- Change Utility.showAlert to disable menus while the alert is being
  shown if caller set disableMenus to true
- Change calls to Utility.showAlert in MPVController methods used
  during startup to use the new disableMenus parameter

The MPVController will show alerts when mpv reports errors. This can
happen while PlayerCore.first is being created. Disabling menus prevents
the MenuController from accessing PlayerCore.first while it is in the
process of being created which was the source of the crash reported in
the issue.

iina/MPVController.swift

@@ -530,7 +530,7 @@ class MPVController: NSObject {
       setOptionString("config", "yes", level: .verbose)
       let status = setOptionString(MPVOption.ProgramBehavior.configDir, userConfDir)
       if status < 0 {
-        Utility.showAlert("extra_option.config_folder", arguments: [userConfDir])
+        Utility.showAlert("extra_option.config_folder", arguments: [userConfDir], disableMenus: true)
       }
     }
 
@@ -543,13 +543,13 @@ class MPVController: NSObject {
             let status = setOptionString(op[0], op[1])
             if status < 0 {
               Utility.showAlert("extra_option.error", arguments:
-                                  [op[0], op[1], status])
+                                  [op[0], op[1], status], disableMenus: true)
             }
           }
           log("Set user configured mpv option values")
         }
       } else {
-        Utility.showAlert("extra_option.cannot_read")
+        Utility.showAlert("extra_option.cannot_read", disableMenus: true)
       }
     }
 
@@ -1589,7 +1589,8 @@ class MPVController: NSObject {
     }
 
     if code < 0 {
-      Utility.showAlert("mpv_error", arguments: [String(cString: mpv_error_string(code)), "\(code)", name])
+      Utility.showAlert("mpv_error", arguments: [String(cString: mpv_error_string(code)), "\(code)", name],
+                        disableMenus: true)
     }
 
     if sync {

iina/MenuController.swift

@@ -968,22 +968,28 @@ class MenuController: NSObject, NSMenuDelegate {
 
   /// Disable all menu items.
   ///
-  /// This method is used during application termination to stop any further input from the user.
+  /// This method is used during application termination to stop any further input from the user and when displaying alerts.
   func disableAllMenus() {
     isDisabled = true
-    disableAllMenuItems(NSApp.mainMenu!)
+    setIsEnabledInAllMenuItems(NSApp.mainMenu!, false)
   }
 
-  /// Disable all menu items in the given menu and any submenus.
+  func enableAllMenus() {
+    isDisabled = false
+    setIsEnabledInAllMenuItems(NSApp.mainMenu!, true)
+  }
+
+  /// Set `isEnabled` to the given value in all menu items in the given menu and any submenus.
   ///
-  /// This method recursively descends through the entire tree of menu items disabling all items.
-  /// - Parameter menu: Menu to disable
-  private func disableAllMenuItems(_ menu: NSMenu) {
+  /// This method recursively descends through the entire tree of menu items setting `isEnabled` in all items.
+  /// - Parameter menu: Menu to disable or enable.
+  /// - Parameter value: Value to set `isEnabled` to.
+  private func setIsEnabledInAllMenuItems(_ menu: NSMenu, _ value: Bool) {
     for item in menu.items {
       if item.hasSubmenu {
-        disableAllMenuItems(item.submenu!)
+        setIsEnabledInAllMenuItems(item.submenu!, value)
       }
-      item.isEnabled = false
+      item.isEnabled = value
     }
   }
 }

iina/Utility.swift

@@ -36,7 +36,7 @@ class Utility {
   typealias InputValidator<T> = (T) -> ValidationResult
 
   // MARK: - Logs, alerts
-  static func showAlert(_ key: String, comment: String? = nil, arguments: [CVarArg]? = nil, style: NSAlert.Style = .critical, sheetWindow: NSWindow? = nil, suppressionKey: PK? = nil) {
+  static func showAlert(_ key: String, comment: String? = nil, arguments: [CVarArg]? = nil, style: NSAlert.Style = .critical, sheetWindow: NSWindow? = nil, suppressionKey: PK? = nil, disableMenus: Bool = false) {
     let alert = NSAlert()
     if let suppressionKey = suppressionKey {
       // This alert includes a suppression button that allows the user to suppress the alert.
@@ -70,11 +70,22 @@ class Utility {
     }
 
     alert.alertStyle = style
+
+    // If an alert occurs early during startup when the first player core is being created then
+    // menus must be disabled while the alert is shown as opening certain menus will cause the menu
+    // controller to attempt to access the player core while it is being initialized resulting in a
+    // crash. See issue #5250.
+    if disableMenus {
+      AppDelegate.shared.menuController.disableAllMenus()
+    }
     if let sheetWindow = sheetWindow {
       alert.beginSheetModal(for: sheetWindow)
     } else {
       alert.runModal()
     }
+    if disableMenus {
+      AppDelegate.shared.menuController.enableAllMenus()
+    }
 
     // If the user asked for this alert to be suppressed set the associated preference.
     if let suppressionButton = alert.suppressionButton, suppressionButton.state == .on {