Improve prefix validation

Author: APickledWalrus

src/main/java/org/skriptlang/skript/bukkit/command/brigadier/RuntimeCommandRegistrar.java

@@ -17,7 +17,6 @@
 import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
 import java.util.Collection;
-import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
@@ -154,10 +153,8 @@ public TemporaryNamePluginMeta(PluginMeta source, String name) {
 		public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
 			if (useAlternativeName) {
 				String methodName = method.getName();
-				if (methodName.equals("getName")) {
+				if (methodName.equals("getName") || methodName.equals("namespace")) {
 					return name;
-				} else if (methodName.equals("namespace")) {
-					return name.toLowerCase(Locale.ROOT);
 				}
 			}
 			return method.invoke(source, args);

src/main/java/org/skriptlang/skript/bukkit/command/elements/structures/util/SubCommandEntryData.java

@@ -190,9 +190,20 @@ public SubCommandEntryData(String key, boolean optional, boolean multiple) {
 		}
 
 		String prefix = entryContainer.getOptional("prefix", String.class, false);
-		if (!isRoot && prefix != null) {
-			Skript.error("Only the root of a command may have a prefix.");
-			return null;
+		if (prefix != null) {
+			if (!isRoot) {
+				Skript.error("Only the root of a command may have a prefix.");
+				return null;
+			}
+			for (char c : prefix.toCharArray()) {
+				if (Character.isWhitespace(c)) {
+					Skript.error("Command prefixes must not have any whitespace.");
+					return null;
+				} else if (c == 167) { // char 167 is §
+					Skript.error("Command prefixes must not have any section symbols.");
+					return null;
+				}
+			}
 		}
 
 		// command requirements