Print field name when meet unexpected token.

closes #12391

core/src/main/java/org/elasticsearch/search/aggregations/bucket/range/geodistance/GeoDistanceParser.java

@@ -145,8 +145,8 @@ public class GeoDistanceParser implements Aggregator.Parser {
                             + currentFieldName + "].", parser.getTokenLocation());
                 }
             } else {
-                throw new SearchParseException(context, "Unexpected token " + token + " in [" + aggregationName + "].",
-                        parser.getTokenLocation());
+                throw new SearchParseException(context, "Unexpected token " + token + " in [" + aggregationName + "]: ["
+                        + currentFieldName + "].", parser.getTokenLocation());
             }
         }