Suppress "branding/image" missing endpoint errors (BL-16300)

src/BloomExe/web/BloomApiHandler.cs

@@ -318,8 +318,11 @@ public async Task<bool> ProcessRequestAsync(IRequestInfo info, string localPath)
                     info.WriteError(404, $"Server could not process {localPath}");
                     return true; // we sort of handled it.
                 }
-                // otherwise it's a programmer error we want to know about.
-                ReportMissingApiEndpoint(info, localPath);
+                if (ShouldReportMissingApiEndpoint(endpointPath))
+                {
+                    // otherwise it's a programmer error we want to know about.
+                    ReportMissingApiEndpoint(info, localPath);
+                }
                 // If the user continues from there, we need to pretend to have handled
                 // the request. Otherwise the caller will keep trying to handle it in
                 // other ways.
@@ -329,6 +332,16 @@ public async Task<bool> ProcessRequestAsync(IRequestInfo info, string localPath)
             return false;
         }
 
+        private static bool ShouldReportMissingApiEndpoint(string endpointPath)
+        {
+            // There are older books out in the wild in which the src for branding images included
+            // this endpoint. We now handle getting branding images differently.
+            // Note that this will eventually result in a 404. That's ok because
+            // the docs in the wild have `onerror="this.style.display='none'"`,
+            // so we don't get the missing image indicator in the preview. See BL-16300.
+            return endpointPath != "branding/image";
+        }
+
         private static void ReportMissingApiEndpoint(IRequestInfo info, string localPath)
         {
             var userMsg = LocalizationManager.GetString(

src/BloomTests/web/BloomServerTests.cs

@@ -8,6 +8,7 @@
 using System.Linq;
 using System.Net;
 using System.Net.Sockets;
+using System.Threading.Tasks;
 using Bloom;
 using Bloom.Api;
 using Bloom.Book;
@@ -226,6 +227,58 @@ public void SupportsHandlerInjection()
             }
         }
 
+        [Test]
+        public async Task MissingLegacyBrandingApiEndpoint_DoesNotReportNonFatalProblem()
+        {
+            using (var server = CreateBloomServer())
+            {
+                server.ApiHandler.RegisterEndpointHandler(
+                    "existingProjectEndpoint",
+                    request => request.ReplyWithText("ok"),
+                    true
+                );
+                NonFatalProblem.LastNonFatalProblemReported = null;
+                var transaction = new PretendRequestInfo(
+                    BloomServer.ServerUrlWithBloomPrefixEndingInSlash
+                        + "api/branding/image?id=back-cover-outside.png"
+                );
+
+                await server.ApiHandler.ProcessRequestAsync(transaction, "api/branding/image");
+
+                Assert.That(transaction.StatusCode, Is.EqualTo(404));
+                Assert.That(transaction.StatusDescription, Is.EqualTo("API endpoint not found"));
+                Assert.That(NonFatalProblem.LastNonFatalProblemReported, Is.Null);
+            }
+        }
+
+        [Test]
+        public async Task MissingNonLegacyApiEndpoint_ReportsNonFatalProblem()
+        {
+            using (var server = CreateBloomServer())
+            {
+                server.ApiHandler.RegisterEndpointHandler(
+                    "existingProjectEndpoint",
+                    request => request.ReplyWithText("ok"),
+                    true
+                );
+                NonFatalProblem.LastNonFatalProblemReported = null;
+                var transaction = new PretendRequestInfo(
+                    BloomServer.ServerUrlWithBloomPrefixEndingInSlash + "api/notARealEndpoint"
+                );
+
+                await server.ApiHandler.ProcessRequestAsync(transaction, "api/notARealEndpoint");
+
+                Assert.That(transaction.StatusCode, Is.EqualTo(404));
+                Assert.That(transaction.StatusDescription, Is.EqualTo("API endpoint not found"));
+                Assert.That(
+                    NonFatalProblem.LastNonFatalProblemReported,
+                    Does.Contain(
+                        "Server could not find an API endpoint for /bloom/api/notARealEndpoint"
+                    )
+                );
+            }
+        }
+
         [Test]
         public void RegisterBoolEndpointHandler_Works()
         {