diff --git a/Lombiq.JsonEditor/Controllers/AdminController.cs b/Lombiq.JsonEditor/Controllers/AdminController.cs
index 93235f7..55b7ab7 100644
--- a/Lombiq.JsonEditor/Controllers/AdminController.cs
+++ b/Lombiq.JsonEditor/Controllers/AdminController.cs
@@ -61,6 +61,8 @@ public AdminController(
     [AdminRoute("Contents/ContentItems/{contentItemId}/Edit/Json")]
     public async Task<IActionResult> Edit(string contentItemId)
     {
+        if (!ModelState.IsValid) return BadRequest(ModelState);
+
         if (string.IsNullOrWhiteSpace(contentItemId) ||
             await _contentManager.GetAsync(contentItemId, VersionOptions.Latest) is not { } contentItem ||
             !await CanEditAsync(contentItem))
@@ -90,6 +92,8 @@ public async Task<IActionResult> EditPost(
         [Bind(Prefix = "submit.Publish")] string submitPublish,
         [Bind(Prefix = "submit.Save")] string submitSave)
     {
+        if (!ModelState.IsValid) return BadRequest(ModelState);
+
         if (string.IsNullOrWhiteSpace(contentItemId) ||
             string.IsNullOrWhiteSpace(json) ||
             JsonConvert.DeserializeObject<ContentItem>(json) is not { } contentItem)
diff --git a/Lombiq.JsonEditor/Models/JsonEditorOptions.cs b/Lombiq.JsonEditor/Models/JsonEditorOptions.cs
index 2a0df8d..885a682 100644
--- a/Lombiq.JsonEditor/Models/JsonEditorOptions.cs
+++ b/Lombiq.JsonEditor/Models/JsonEditorOptions.cs
@@ -45,7 +45,7 @@ public JsonEditorMode Mode
         set => ModeString = GetModeString(value);
     }
 
-    public IEnumerable<string> Modes { get; set; } = new[] { "tree", "view", "form", "code", "text", "preview" };
+    public IEnumerable<string> Modes { get; set; } = ["tree", "view", "form", "code", "text", "preview"];
 
     /// <summary>
     /// Gets or sets the JSON Schema to validate against. A JSON schema describes the structure that a JSON object must
@@ -116,8 +116,8 @@ private static string GetModeString(JsonEditorMode mode) =>
     public static JsonEditorOptions GetSample(IHtmlLocalizer localizer) =>
         new()
         {
-            Templates = new[]
-            {
+            Templates =
+            [
                 new JsonEditorTemplate
                 {
                     Field = "aTechnicalNameThatHasToBeUnique",
@@ -127,6 +127,6 @@ public static JsonEditorOptions GetSample(IHtmlLocalizer localizer) =>
                         .Value,
                     Value = new { YourObject = "goes here" },
                 },
-            },
+            ],
         };
 }
diff --git a/Lombiq.JsonEditor/Services/JsonEditorContentSecurityPolicyProvider.cs b/Lombiq.JsonEditor/Services/JsonEditorContentSecurityPolicyProvider.cs
index 27cd27d..722b071 100644
--- a/Lombiq.JsonEditor/Services/JsonEditorContentSecurityPolicyProvider.cs
+++ b/Lombiq.JsonEditor/Services/JsonEditorContentSecurityPolicyProvider.cs
@@ -1,4 +1,4 @@
-using Lombiq.HelpfulLibraries.AspNetCore.Security;
+using Lombiq.HelpfulLibraries.AspNetCore.Security;
 using Lombiq.JsonEditor.Constants;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.DependencyInjection;
@@ -18,7 +18,7 @@ public class JsonEditorContentSecurityPolicyProvider : ResourceManagerContentSec
 {
     protected override string ResourceType => "script";
     protected override string ResourceName => ResourceNames.Library;
-    protected override IReadOnlyCollection<string> DirectiveNameChain { get; } = new[] { WorkerSrc, ScriptSrc };
+    protected override IReadOnlyCollection<string> DirectiveNameChain { get; } = [WorkerSrc, ScriptSrc];
     protected override string DirectiveValue => $"{Blob} {Data}";
 
     protected override ValueTask ThenUpdateAsync(