Fix tab completion when *not* using %.

- Also allow tab-completion of % pattern when it's the first/only pattern being used
 - Also don't error when attempting to tab complete an invalid percent value

worldedit-core/src/main/java/com/fastasyncworldedit/core/extension/factory/parser/pattern/RichPatternParser.java

@@ -32,6 +32,8 @@ import java.util.stream.Stream;
 
 public class RichPatternParser extends FaweParser<Pattern> {
 
+    private static final java.util.regex.Pattern percentPatternRegex = java.util.regex.Pattern.compile("[0-9]+(\\.[0-9]*)?%.*");
+
     /**
      * Create a new rich pattern-parser.
      *
@@ -110,7 +112,7 @@ public class RichPatternParser extends FaweParser<Pattern> {
                             pattern = parseFromInput(command.substring(1, end == -1 ? command.length() : end), context);
                         } else {
                             int percentIndex = command.indexOf('%');
-                            if (percentIndex != -1) {  // Legacy percent pattern
+                            if (percentIndex != -1 && percentPatternRegex.matcher(command).matches()) {  // Legacy percent pattern
                                 chance = Expression.compile(command.substring(0, percentIndex)).evaluate();
                                 String value = command.substring(percentIndex + 1);
                                 if (!entry.getValue().isEmpty()) {

worldedit-core/src/main/java/com/sk89q/worldedit/extension/factory/parser/pattern/RandomPatternParser.java

@@ -15,6 +15,8 @@ import java.util.stream.Stream;
 
 public class RandomPatternParser extends InputParser<Pattern> {
 
+    private static final java.util.regex.Pattern regex = java.util.regex.Pattern.compile("[0-9]+(\\.[0-9]*)?%.*");
+
     /**
      * Create a new input parser.
      *
@@ -28,26 +30,35 @@ public class RandomPatternParser extends InputParser<Pattern> {
     public Stream<String> getSuggestions(String input) {
         //FAWE start
         List<String> patterns = StringUtil.split(input, ',', '[', ']');
-        if (patterns.size() == 1) {
+        if (patterns.size() == 0) {
             return Stream.empty();
         }
         // get suggestions for the last token only
         String token = patterns.get(patterns.size() - 1);
-        String randString = "";
-        String previous = String.join(",", patterns.subList(0, patterns.size() - 1));
-        if (token.matches("[0-9]+(\\.[0-9]*)?%.*")) {
+        String percent;
+        String previous;
+        if (patterns.size() != 1) {
+            previous = String.join(",", patterns.subList(0, patterns.size() - 1));
+            percent = ",";
+        } else {
+            previous = "";
+            percent = "";
+        }
+        if (regex.matcher(token).matches()) {
             String[] p = token.split("%");
             if (p.length < 2) {
                 return Stream.empty();
             } else {
-                randString = p[0];
+                percent += p[0] + "%";
                 token = p[1];
             }
+        } else {
+            return Stream.empty();
         }
         final List<String> innerSuggestions = worldEdit.getPatternFactory().getSuggestions(token);
-        String prev = previous + "," + randString + "%";
-        return innerSuggestions.stream().map(s -> prev + s);
+        String prefix = previous + percent;
         //FAWE end
+        return innerSuggestions.stream().map(s -> prefix + s);
     }
 
     @Override