Context: try hard not to die in non-strict mode

When Context#inject(Object) is called, there are all kinds of crazy
things that can potentially happen, particularly class loading failures
(e.g., NoClassDefFoundError) due to missing dependencies when scanning
the given object's fields and methods.

When the context is in non-strict mode, we want to try very hard not to
throw an exception, but instead simply log an error, when something goes
wrong during the injection. And we want the injection to proceed
tenaciously, so that if something goes wrong at one stage, other stages
still might complete successfully.

This commit is best viewed with git's "-b" flag.

Author: ctrueden

src/main/java/org/scijava/Context.java

@@ -42,6 +42,7 @@
 import org.scijava.event.ContextDisposingEvent;
 import org.scijava.event.EventHandler;
 import org.scijava.event.EventService;
+import org.scijava.log.LogService;
 import org.scijava.plugin.Parameter;
 import org.scijava.plugin.PluginIndex;
 import org.scijava.service.Service;
@@ -400,46 +401,72 @@ public static List<Class<? extends Service>> serviceClassList(
 	// -- Helper methods --
 
 	private List<Field> getParameterFields(Object o) {
-		return ClassUtils.getAnnotatedFields(o.getClass(), Parameter.class);
+		try {
+			return ClassUtils.getAnnotatedFields(o.getClass(), Parameter.class);
+		}
+		catch (final Throwable t) {
+			handleSafely(t);
+		}
+		return Collections.emptyList();
 	}
 
 	private void inject(final Field f, final Object o) {
-		f.setAccessible(true); // expose private fields
-
-		final Class<?> type = f.getType();
-		if (Service.class.isAssignableFrom(type)) {
-			final Service existingService = (Service) ClassUtils.getValue(f, o);
-			if (existingService != null) {
-				throw new IllegalStateException("Context already injected: " +
-						f.getDeclaringClass().getName() + "#" + f.getName());
+		try {
+			f.setAccessible(true); // expose private fields
+
+			final Class<?> type = f.getType();
+			if (Service.class.isAssignableFrom(type)) {
+				final Service existingService = (Service) ClassUtils.getValue(f, o);
+				if (existingService != null) {
+					throw new IllegalStateException("Context already injected: " +
+							f.getDeclaringClass().getName() + "#" + f.getName());
+				}
+
+				// populate Service parameter
+				@SuppressWarnings("unchecked")
+				final Class<? extends Service> serviceType =
+				(Class<? extends Service>) type;
+				final Service service = getService(serviceType);
+				if (service == null && f.getAnnotation(Parameter.class).required()) {
+					throw new IllegalArgumentException(
+						createMissingServiceMessage(serviceType));
+				}
+				ClassUtils.setValue(f, o, service);
 			}
-
-			// populate Service parameter
-			@SuppressWarnings("unchecked")
-			final Class<? extends Service> serviceType =
-			(Class<? extends Service>) type;
-			final Service service = getService(serviceType);
-			if (service == null && f.getAnnotation(Parameter.class).required()) {
-				throw new IllegalArgumentException(
-					createMissingServiceMessage(serviceType));
+			else if (Context.class.isAssignableFrom(type) && type.isInstance(this)) {
+				final Context existingContext = (Context) ClassUtils.getValue(f, o);
+				if (existingContext != null) {
+					throw new IllegalStateException("Context already injected: " +
+							f.getDeclaringClass().getName() + "#" + f.getName());
+				}
+
+				// populate Context parameter
+				ClassUtils.setValue(f, o, this);
 			}
-			ClassUtils.setValue(f, o, service);
 		}
-		else if (Context.class.isAssignableFrom(type) && type.isInstance(this)) {
-			final Context existingContext = (Context) ClassUtils.getValue(f, o);
-			if (existingContext != null) {
-				throw new IllegalStateException("Context already injected: " +
-						f.getDeclaringClass().getName() + "#" + f.getName());
-			}
-
-			// populate Context parameter
-			ClassUtils.setValue(f, o, this);
+		catch (final Throwable t) {
+			handleSafely(t);
 		}
 	}
 
 	private void subscribeToEvents(final Object o) {
-		final EventService eventService = getService(EventService.class);
-		if (eventService != null) eventService.subscribe(o);
+		try {
+			final EventService eventService = getService(EventService.class);
+			if (eventService != null) eventService.subscribe(o);
+		}
+		catch (final Throwable t) {
+			handleSafely(t);
+		}
+	}
+
+	private void handleSafely(final Throwable t) {
+		if (isStrict()) {
+			// NB: Only rethrow unchecked exceptions.
+			if (t instanceof RuntimeException) throw (RuntimeException) t;
+			if (t instanceof Error) throw (Error) t;
+		}
+		final LogService log = getService(LogService.class);
+		if (log != null) log.error(t);
 	}
 
 	private String createMissingServiceMessage(