Fall back to internal stylesheet when loading external stuff fails.

Refs #24099

src/main/java/info/textgrid/services/aggregator/html/HTMLWriter.java

@@ -189,18 +189,22 @@ void detectEmbeddedStylesheet(final Source source) {
 
 	private XsltExecutable getStylesheet() throws SaxonApiException,
 			IOException {
-		if (explicitStylesheetURI.isPresent()) {
-			actualStylesheetLabel = explicitStylesheetURI.get().toString() + " (explicit)";
-			return stylesheetManager.getStylesheet(explicitStylesheetURI.get(), getSid(),
-					refreshStylesheet, false);
-		} else if (associatedStylesheetURI.isPresent()) {
-			actualStylesheetLabel = associatedStylesheetURI.get().toString() + " (associated)";
-			return stylesheetManager.getStylesheet(associatedStylesheetURI.get(), getSid(),
-					refreshStylesheet, false);
-		} else {
-			actualStylesheetLabel = "(internal)";
-			return stylesheetManager.getStylesheet(TO_HTML_XSL, getSid(), false, true);
+		try {
+            if (explicitStylesheetURI.isPresent()) {
+                actualStylesheetLabel = explicitStylesheetURI.get().toString() + " (explicit)";
+                return stylesheetManager.getStylesheet(explicitStylesheetURI.get(), getSid(),
+                        refreshStylesheet, false);
+            } else if (associatedStylesheetURI.isPresent()) {
+                actualStylesheetLabel = associatedStylesheetURI.get().toString() + " (associated)";
+                return stylesheetManager.getStylesheet(associatedStylesheetURI.get(), getSid(),
+                        refreshStylesheet, false);
+            };
+		} catch (final SaxonApiException e) {
+			logger.log(Level.WARNING, MessageFormat.format("Failed to load stylesheet {0}, falling back to internal",
+					actualStylesheetLabel), e);
 		}
+        actualStylesheetLabel = "(internal)";
+        return stylesheetManager.getStylesheet(TO_HTML_XSL, getSid(), false, true);
 	}
 
 	private Source getSource() throws ObjectNotFoundFault, MetadataParseFault, IoFault, ProtocolNotImplementedFault, AuthFault, IOException {