Fix IndexOutOfBoundsException (#198)

if stringBuffer only contains "$" we can't peek at the next character, so make sure that there are enough character to peek at.

src/main/java/codes/cookies/mod/services/item/search/SearchQueryMatcher.java

@@ -57,7 +57,7 @@ public static Optional<Builder> parse(String rawQuery) {
 				builder.negate();
 			}
 
-			if (stringBuffer.peek() == '$' && stringBuffer.peek(1) == ':') {
+			if (stringBuffer.canRead(2) && stringBuffer.peek() == '$' && stringBuffer.peek(1) == ':') {
 				stringBuffer.skip();
 				stringBuffer.skip();
 				builder.regex();