refactor: Enable lint use_build_context_synchronously

lib/utils/url_launcher.dart

@@ -27,6 +27,8 @@ class UrlLauncher {
   const UrlLauncher(this.context, this.url, [this.name]);
 
   Future<void> launchUrl() async {
+    final l10n = L10n.of(context);
+    final scaffoldMessenger = ScaffoldMessenger.of(context);
     if (url!.toLowerCase().startsWith(AppConfig.deepLinkPrefix) ||
         url!.toLowerCase().startsWith(AppConfig.inviteLinkPrefix) ||
         {'#', '@', '!', '+', '\$'}.contains(url![0]) ||
@@ -36,8 +38,8 @@ class UrlLauncher {
     final uri = Uri.tryParse(url!);
     if (uri == null) {
       // we can't open this thing
-      ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text(L10n.of(context).cantOpenUri(url!))),
+      scaffoldMessenger.showSnackBar(
+        SnackBar(content: Text(l10n.cantOpenUri(url!))),
       );
       return;
     }
@@ -47,10 +49,10 @@ class UrlLauncher {
       // that the user can see the actual url before opening the browser.
       final consent = await showOkCancelAlertDialog(
         context: context,
-        title: L10n.of(context).openLinkInBrowser,
+        title: l10n.openLinkInBrowser,
         message: url,
-        okLabel: L10n.of(context).open,
-        cancelLabel: L10n.of(context).cancel,
+        okLabel: l10n.open,
+        cancelLabel: l10n.cancel,
       );
       if (consent != OkCancelResult.ok) return;
     }
@@ -90,8 +92,8 @@ class UrlLauncher {
       return;
     }
     if (uri.host.isEmpty) {
-      ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text(L10n.of(context).cantOpenUri(url!))),
+      scaffoldMessenger.showSnackBar(
+        SnackBar(content: Text(l10n.cantOpenUri(url!))),
       );
       return;
     }
@@ -161,6 +163,7 @@ class UrlLauncher {
         }
       }
       servers.addAll(identityParts.via);
+      if (!context.mounted) return;
       if (room != null) {
         if (room.isSpace) {
           // TODO: Implement navigate to space
@@ -178,6 +181,7 @@ class UrlLauncher {
         }
         return;
       } else {
+        if (!context.mounted) return;
         await showAdaptiveDialog(
           context: context,
           builder: (c) =>
@@ -185,6 +189,7 @@ class UrlLauncher {
         );
       }
       if (roomIdOrAlias.sigil == '!') {
+        if (!context.mounted) return;
         if (await showOkCancelAlertDialog(
               useRootNavigator: false,
               context: context,
@@ -192,6 +197,7 @@ class UrlLauncher {
             ) ==
             OkCancelResult.ok) {
           roomId = roomIdOrAlias;
+          if (!context.mounted) return;
           final response = await showFutureLoadingDialog(
             context: context,
             future: () => matrix.client.joinRoom(
@@ -200,11 +206,13 @@ class UrlLauncher {
             ),
           );
           if (response.error != null) return;
+          if (!context.mounted) return;
           // wait for two seconds so that it probably came down /sync
           await showFutureLoadingDialog(
             context: context,
             future: () => Future.delayed(const Duration(seconds: 2)),
           );
+          if (!context.mounted) return;
           if (event != null) {
             context.go(
               Uri(
@@ -228,6 +236,7 @@ class UrlLauncher {
               return Profile(userId: userId);
             }),
       );
+      if (!context.mounted) return;
       await UserDialog.show(
         context: context,
         profile: profileResult.result!,