The `ignore_malformed` option is supported by a few of our field types, mainly numerics and dates, to still accept the document when such fields hold malformed values. See https://www.elastic.co/guide/en/elasticsearch/reference/current/ignore-malformed.html. Also `ignore_malformed` is an index level setting that gets applied to all field types that support it. 

The boolean field type does not support `ignore_malformed` but it should, so that if a boolean field cannot be parsed as a boolean, the document can still be accepted.


server/src/main/java/org/elasticsearch/index/mapper/BooleanFieldMapper.java
builder.add(termQuery(value, context), BooleanClause.Occur.SHOULD);
                }
                return new ConstantScoreQuery(builder.build());
            }
        }
        @Override
        public Query rangeQuery(
            Object lowerTerm,
            Object upperTerm,
            boolean includeLower,
            boolean includeUpper,
            SearchExecutionContext context
        ) {
            failIfNotIndexedNorDocValuesFallback(context);
            if (isIndexed()) {
                return new TermRangeQuery(
                    name(),
                    lowerTerm == null ? null : indexedValueForSearch(lowerTerm),
                    upperTerm == null ? null : indexedValueForSearch(upperTerm),
                    includeLower,
                    includeUpper
                );
            } else {
                long l = 0;
                long u = 1;
                if (lowerTerm != null) {
                    l = docValueForSearch(lowerTerm);
                    if (includeLower == false) {
                        l = Math.max(1, l + 1);
                    }