Add optional safety checks for addons

pom.xml

@@ -2,7 +2,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>ch.njol</groupId>
 	<artifactId>skript</artifactId>
-	<version>2.2-dev13b</version>
+	<version>2.2-dev13c</version>
 	<name>Skript</name>
 	<description>A plugin for the Minecraft server API Bukkit that allows to create scripts in natural language.</description>
 	<url>http://njol.ch/projects/skript/</url>

src/main/java/ch/njol/skript/SkriptConfig.java

@@ -163,6 +163,9 @@ public EventPriority convert(final String s) {
 	public final static Option<Boolean> keepConfigsLoaded = new Option<Boolean>("keep configs loaded", false)
 			.optional(true);
 
+	public final static Option<Boolean> addonSafetyChecks = new Option<Boolean>("addon safety checks", false)
+			.optional(true);
+
 	/**
 	 * This should only be used in special cases
 	 */

src/main/java/ch/njol/skript/registrations/Classes.java

@@ -33,6 +33,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
 import java.util.regex.Pattern;
@@ -44,6 +45,7 @@
 
 import ch.njol.skript.Skript;
 import ch.njol.skript.SkriptAPIException;
+import ch.njol.skript.SkriptConfig;
 import ch.njol.skript.classes.ClassInfo;
 import ch.njol.skript.classes.Converter;
 import ch.njol.skript.classes.Converter.ConverterInfo;
@@ -126,6 +128,9 @@ public final static void onRegistrationsStop() {
 	private final static void sortClassInfos() {
 		assert classInfos == null;
 
+		if (!Skript.testing() && SkriptConfig.addonSafetyChecks.value())
+			removeNullElements();
+
 		// merge before, after & sub/supertypes in after
 		for (final ClassInfo<?> ci : tempClassInfos) {
 			final Set<String> before = ci.before();
@@ -215,6 +220,16 @@ private final static void sortClassInfos() {
 
 	}
 
+	@SuppressWarnings({"null", "unused"})
+	private final static void removeNullElements() {
+		Iterator<ClassInfo<?>> it = tempClassInfos.iterator();
+		while (it.hasNext()) {
+			ClassInfo<?> ci = it.next();
+			if (ci.getC() == null)
+				it.remove();
+		}
+	}
+
 	private final static void checkAllowClassInfoInteraction() {
 		if (Skript.isAcceptRegistrations())
 			throw new IllegalStateException("Cannot use classinfos until registration is over");