Add utility for safe pattern compiling

src/main/java/fr/xephi/authme/util/Utils.java

@@ -10,6 +10,7 @@ import org.bukkit.OfflinePlayer;
 import org.bukkit.entity.Player;
 
 import java.util.Arrays;
+import java.util.regex.Pattern;
 
 /**
  * Utility class for various operations used in the codebase.
@@ -79,6 +80,15 @@ public final class Utils {
         }
     }
 
+    public static Pattern safePatternCompile(String pattern) {
+        try {
+            return Pattern.compile(pattern);
+        } catch (Exception e) {
+            ConsoleLogger.showError("Failed to compile pattern '" + pattern + "' - defaulting to allowing everything");
+            return Pattern.compile(".*?");
+        }
+    }
+
     /**
      * Returns the IP of the given player.
      *

src/main/java/fr/xephi/authme/util/ValidationService.java

@@ -38,7 +38,7 @@ public class ValidationService implements Reloadable {
 
     @Override
     public void reload() {
-        passwordRegex = Pattern.compile(settings.getProperty(RestrictionSettings.ALLOWED_PASSWORD_REGEX));
+        passwordRegex = Utils.safePatternCompile(settings.getProperty(RestrictionSettings.ALLOWED_PASSWORD_REGEX));
     }
 
     /**