ensure that image changes are always accessible

Sources/App/CapServer.swift

@@ -84,6 +84,7 @@ final class CapServer: ServerOwner {
         try loadCaps()
         try updateCounts()
         saveCapCountHTML()
+        try ensureExistenceOfChangedImagesFile()
     }
 
     private func loadClassifierVersion(at url: URL) {
@@ -257,9 +258,6 @@ final class CapServer: ServerOwner {
         guard !unwrittenImageChanges.isEmpty else {
             return
         }
-        if !fm.fileExists(atPath: changedImagesFile.path) {
-            try Data().write(to: changedImagesFile)
-        }
         
         let handle = try FileHandle(forWritingTo: changedImagesFile)
         try handle.seekToEnd()
@@ -286,14 +284,23 @@ final class CapServer: ServerOwner {
         }
     }
     
-    func deleteChangedImageListFile() {
+    private func ensureExistenceOfChangedImagesFile() throws {
-        guard fm.fileExists(atPath: changedImagesFile.path) else {
+        guard !fm.fileExists(atPath: changedImagesFile.path) else {
             return
         }
         do {
-            try fm.removeItem(at: changedImagesFile)
+            try Data().write(to: changedImagesFile)
         } catch {
-            log("Failed to delete changed images file: \(error)")
+            log("Failed to create changed images file: \(error)")
+            throw error
+        }
+    }
+    
+    func emptyChangedImageListFile() {
+        do {
+            try Data().write(to: changedImagesFile)
+        } catch {
+            log("Failed to empty changed images file: \(error)")
         }
     }
     

Sources/App/routes.swift

@@ -82,6 +82,6 @@ func routes(_ app: Application) {
     // Reset the changed images list
     app.postCatching("changes") { request in
         try authorize(request)
-        server.deleteChangedImageListFile()
+        server.emptyChangedImageListFile()
     }
 }