Fix error handler controllers failing test-compilation (#593)

Co-authored-by: Rob Bygrave <robin.bygrave@gmail.com>

Author: SentryMan

http-generator-core/src/main/java/io/avaje/http/generator/core/BaseProcessor.java

@@ -187,8 +187,8 @@ private void writeClientAdapter(ControllerReader reader) {
 
     try {
       if (reader.beanType().getInterfaces().isEmpty()
-          && "java.lang.Object".equals(reader.beanType().getSuperclass().toString())) {
-        new TestClientWriter(reader).write();
+          && "java.lang.Object".equals(reader.beanType().getSuperclass().toString())
+          && new TestClientWriter(reader).write()) {
         clientFQNs.add(reader.beanType().getQualifiedName().toString() + "TestAPI");
       }
     } catch (final IOException e) {

http-generator-core/src/main/java/io/avaje/http/generator/core/TestClientWriter.java

@@ -54,12 +54,13 @@ protected String initPackageName(String originName) {
     return dp > -1 ? originName.substring(0, dp) : null;
   }
 
-  void write() {
-    if (methods.isEmpty()) return;
+  boolean write() {
+    if (methods.isEmpty()) return false;
     writePackage();
     writeImports();
     writeClassStart();
     writeAddRoutes();
+    return true;
   }
 
   protected void writePackage() {

tests/test-jex/src/main/java/org/example/web/ErrorController.java

@@ -0,0 +1,29 @@
+package org.example.web;
+
+import io.avaje.http.api.Controller;
+import io.avaje.http.api.ExceptionHandler;
+import io.avaje.http.api.Filter;
+import io.avaje.http.api.Produces;
+import io.avaje.jex.http.Context;
+import io.avaje.jex.http.HttpFilter.FilterChain;
+
+@Controller
+public class ErrorController {
+
+  @Filter
+  void filter(FilterChain chain) {
+    // do nothing
+    chain.proceed();
+  }
+
+  @ExceptionHandler
+  String exception(RuntimeException ex) {
+    return "Err: " + ex;
+  }
+
+  @Produces(statusCode = 501)
+  @ExceptionHandler
+  HelloDto exceptionCtx(IllegalAccessException ex, Context ctx) {
+    return null;
+  }
+}