Wrap failures in the woven final-field writer like the runtime accessor

core/src/main/java/dev/morphia/critter/parser/generator/AddFieldAccessorMethods.java

@@ -24,6 +24,7 @@
 public class AddFieldAccessorMethods extends AccessorMethods {
     private static final ClassDesc CD_FIELD = ClassDesc.of("java.lang.reflect.Field");
     private static final ClassDesc CD_CRITTER = ClassDesc.of("dev.morphia.critter.Critter");
+    private static final ClassDesc CD_RUNTIME_EXCEPTION = ClassDesc.of("java.lang.RuntimeException");
     private final List<FieldInfo> fields;
 
     /**
@@ -123,15 +124,32 @@ private static void writeFinalField(ClassBuilder classBuilder, ClassDesc entityD
             cod.dup();
             cod.putstatic(entityDesc, cacheName, CD_FIELD);
             cod.labelBinding(cached);
-            cod.aload(0);
-            cod.loadLocal(kind, 1);
-            if (kind != TypeKind.REFERENCE) {
-                ClassDesc wrapper = ClassDesc.of(GenerationUtils.PRIMITIVE_TO_WRAPPER.get(fieldDesc.displayName()));
-                cod.invokestatic(wrapper, "valueOf", MethodTypeDesc.of(wrapper, fieldDesc));
-            }
-            cod.invokevirtual(CD_FIELD, "set", MethodTypeDesc.of(ConstantDescs.CD_void, ConstantDescs.CD_Object,
-                    ConstantDescs.CD_Object));
-            cod.return_();
+            int fieldSlot = cod.allocateLocal(TypeKind.REFERENCE);
+            cod.astore(fieldSlot);
+            // Wrap failures the same way the runtime accessor (NestmateAccessorGenerator) does, so both tiers fail alike
+            // and Field.set's checked IllegalAccessException doesn't escape undeclared.
+            cod.trying(tryBody -> {
+                tryBody.aload(fieldSlot);
+                tryBody.aload(0);
+                tryBody.loadLocal(kind, 1);
+                if (kind != TypeKind.REFERENCE) {
+                    ClassDesc wrapper = ClassDesc.of(GenerationUtils.PRIMITIVE_TO_WRAPPER.get(fieldDesc.displayName()));
+                    tryBody.invokestatic(wrapper, "valueOf", MethodTypeDesc.of(wrapper, fieldDesc));
+                }
+                tryBody.invokevirtual(CD_FIELD, "set", MethodTypeDesc.of(ConstantDescs.CD_void, ConstantDescs.CD_Object,
+                        ConstantDescs.CD_Object));
+                tryBody.return_();
+            }, catches -> catches.catching(ConstantDescs.CD_Exception, catchBody -> {
+                int exceptionSlot = catchBody.allocateLocal(TypeKind.REFERENCE);
+                catchBody.astore(exceptionSlot);
+                catchBody.new_(CD_RUNTIME_EXCEPTION);
+                catchBody.dup();
+                catchBody.ldc("Failed to set final field '%s'".formatted(field.name()));
+                catchBody.aload(exceptionSlot);
+                catchBody.invokespecial(CD_RUNTIME_EXCEPTION, "<init>",
+                        MethodTypeDesc.of(ConstantDescs.CD_void, ConstantDescs.CD_String, ConstantDescs.CD_Throwable));
+                catchBody.athrow();
+            }));
         });
     }
 }

core/src/test/java/dev/morphia/critter/parser/generator/TestGeneration.java

@@ -1,6 +1,7 @@
 package dev.morphia.critter.parser.generator;
 
 import java.io.File;
+import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
@@ -171,6 +172,26 @@ public void testGeneratorFinalFields() throws Exception {
         assertRoundTrip(model, entity, "count", 42);
     }
 
+    @Test
+    @SuppressWarnings({ "unchecked", "rawtypes" })
+    public void testGeneratorFinalFieldWriteFailureIsWrapped() throws Exception {
+        EntityModel model = generateModel(FinalFieldsExample.class);
+        Class<?> woven = critterClassLoader.loadClass(FinalFieldsExample.class.getName());
+        Object entity = woven.getConstructor(String.class, int.class).newInstance("initial", 1);
+
+        // Seed the woven writer's Field cache with a copy that was never made accessible, so Field.set throws the
+        // checked IllegalAccessException.
+        Field cache = woven.getDeclaredField("__fieldCode");
+        cache.setAccessible(true);
+        cache.set(null, woven.getDeclaredField("code"));
+
+        PropertyAccessor accessor = model.getProperty("code").getAccessor();
+        Throwable thrown = Assertions.assertThrows(Throwable.class, () -> accessor.set(entity, "updated"));
+        Assertions.assertEquals(RuntimeException.class, thrown.getClass());
+        Assertions.assertEquals("Failed to set final field 'code'", thrown.getMessage());
+        Assertions.assertInstanceOf(IllegalAccessException.class, thrown.getCause());
+    }
+
     @Test
     public void testRuntimeGeneratorFinalFields() throws Exception {
         // A fresh loader: runtime mode leaves the entity class alone, so it must resolve to the application's copy.