QuteErrorPageSetup: support templates that are not backed by a file

- fixes quarkusio#44412

extensions/qute/deployment/src/main/java/io/quarkus/qute/deployment/QuteDevModeProcessor.java

@@ -0,0 +1,31 @@
+package io.quarkus.qute.deployment;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import io.quarkus.arc.deployment.ValidationPhaseBuildItem.ValidationErrorBuildItem;
+import io.quarkus.deployment.IsDevelopment;
+import io.quarkus.deployment.annotations.BuildProducer;
+import io.quarkus.deployment.annotations.BuildStep;
+import io.quarkus.deployment.annotations.BuildSteps;
+import io.quarkus.dev.console.DevConsoleManager;
+import io.quarkus.qute.runtime.devmode.QuteErrorPageSetup;
+
+@BuildSteps(onlyIf = IsDevelopment.class)
+public class QuteDevModeProcessor {
+
+    @BuildStep
+    void collectGeneratedContents(List<TemplatePathBuildItem> templatePaths,
+            BuildProducer<ValidationErrorBuildItem> errors) {
+        Map<String, String> contents = new HashMap<>();
+        for (TemplatePathBuildItem template : templatePaths) {
+            if (!template.isFileBased()) {
+                contents.put(template.getPath(), template.getContent());
+            }
+        }
+        // Set the global that could be used at runtime when a qute error page is rendered
+        DevConsoleManager.setGlobal(QuteErrorPageSetup.GENERATED_CONTENTS, contents);
+    }
+
+}

extensions/qute/runtime/src/main/java/io/quarkus/qute/runtime/devmode/QuteErrorPageSetup.java

@@ -2,6 +2,7 @@
 
 import java.io.BufferedReader;
 import java.io.IOException;
+import java.io.StringReader;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.nio.file.Files;
@@ -12,13 +13,15 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.ListIterator;
+import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionStage;
 import java.util.stream.Collectors;
 
 import org.jboss.logging.Logger;
 
 import io.quarkus.dev.ErrorPageGenerators;
+import io.quarkus.dev.console.DevConsoleManager;
 import io.quarkus.dev.spi.HotReplacementContext;
 import io.quarkus.dev.spi.HotReplacementSetup;
 import io.quarkus.qute.Engine;
@@ -33,6 +36,8 @@ public class QuteErrorPageSetup implements HotReplacementSetup {
 
     private static final Logger LOG = Logger.getLogger(QuteErrorPageSetup.class);
 
+    public static final String GENERATED_CONTENTS = "io.quarkus.qute.generatedContents";
+
     private static final String TEMPLATE_EXCEPTION = "io.quarkus.qute.TemplateException";
     private static final String ORIGIN = "io.quarkus.qute.TemplateNode$Origin";
 
@@ -139,6 +144,10 @@ String getProblemInfo(int index, Throwable problem, Template problemTemplate, Es
             LOG.warn("Unable to read the template source: " + templateId, e);
         }
 
+        if (sourceLines.isEmpty()) {
+            return Arrays.stream(messageLines).collect(Collectors.joining("<br>"));
+        }
+
         List<Integer> realLines = new ArrayList<>();
         boolean endLinesSkipped = false;
         if (sourceLines.size() > 15) {
@@ -187,6 +196,14 @@ private BufferedReader getBufferedReader(String templateId) throws IOException {
                 }
             }
         }
+        // Source file not available - try to search the generated contents
+        Map<String, String> generatedContents = DevConsoleManager.getGlobal(GENERATED_CONTENTS);
+        if (generatedContents != null) {
+            String template = generatedContents.get(templateId);
+            if (template != null) {
+                return new BufferedReader(new StringReader(template));
+            }
+        }
         throw new IllegalStateException("Template source not available");
     }