Fix webserver stalling

Author: TBlueF

BlueMapCommon/src/main/java/de/bluecolored/bluemap/common/web/FileRequestHandler.java

@@ -36,6 +36,7 @@
 import java.nio.file.InvalidPathException;
 import java.nio.file.Path;
 import java.time.Instant;
+import java.time.ZoneOffset;
 import java.time.format.DateTimeFormatter;
 import java.time.format.DateTimeParseException;
 import java.util.concurrent.TimeUnit;
@@ -134,7 +135,10 @@ private HttpResponse generateResponse(HttpRequest request) throws IOException {
         //create response
         HttpResponse response = new HttpResponse(HttpStatusCode.OK);
         response.addHeader("ETag", eTag);
-        if (lastModified > 0) response.addHeader("Last-Modified", DateTimeFormatter.RFC_1123_DATE_TIME.format(Instant.ofEpochMilli(lastModified)));
+        if (lastModified > 0) response.addHeader("Last-Modified", DateTimeFormatter.RFC_1123_DATE_TIME.format(Instant
+                .ofEpochMilli(lastModified)
+                .atOffset(ZoneOffset.UTC)
+        ));
         response.addHeader("Cache-Control", "public");
         response.addHeader("Cache-Control", "max-age=" + TimeUnit.DAYS.toSeconds(1));
 

BlueMapCommon/src/main/java/de/bluecolored/bluemap/common/web/http/HttpConnection.java

@@ -87,13 +87,20 @@ public void accept(SelectionKey selectionKey) {
                         () -> requestHandler.handle(request),
                         responseHandlerExecutor
                 );
-                futureResponse.thenAccept(response -> {
+                futureResponse.handle((response, error) -> {
+                    if (error != null) {
+                        Logger.global.logError("Unexpected error handling request", error);
+                        response = new HttpResponse(HttpStatusCode.INTERNAL_SERVER_ERROR);
+                    }
+
                     try {
                         response.read(channel); // do an initial read to trigger response sending intent
                         this.response = response;
                     } catch (IOException e) {
                         handleIOException(channel, e);
                     }
+
+                    return null;
                 });
             }