GOCBC-907: Add extra search error fields

Motivation
----------
At the moment when we get an unknown search error we return an error
with "search error | {...}" the information contained doesn't actually
cover why the search failed. This detail is already exposed from
gocbcore we just aren't exposing it in gocb.

Changes
-------
Update error wrapping to handle search errors.
Add ErrorText and IndexName fields to SearchError.

Change-Id: Id458cdc56e767aa655087ebd78001883b04fd465
Reviewed-on: http://review.couchbase.org/c/gocb/+/129529
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Charles Dixon <chvckd@gmail.com>

error_search.go

@@ -8,6 +8,8 @@ type SearchError struct {
 	Endpoint      string        `json:"endpoint,omitempty"`
 	RetryReasons  []RetryReason `json:"retry_reasons,omitempty"`
 	RetryAttempts uint32        `json:"retry_attempts,omitempty"`
+	ErrorText     string        `json:"error_text"`
+	IndexName     string        `json:"index_name,omitempty"`
 }
 
 // Error returns the string representation of this error.

error_wrapping.go

@@ -68,6 +68,17 @@ func maybeEnhanceCoreErr(err error) error {
 			RetryAttempts:   analyticsErr.RetryAttempts,
 		}
 	}
+	if searchErr, ok := err.(*gocbcore.SearchError); ok {
+		return &SearchError{
+			InnerError:    searchErr.InnerError,
+			Query:         searchErr.Query,
+			Endpoint:      searchErr.Endpoint,
+			RetryReasons:  translateCoreRetryReasons(searchErr.RetryReasons),
+			RetryAttempts: searchErr.RetryAttempts,
+			ErrorText:     searchErr.ErrorText,
+			IndexName:     searchErr.IndexName,
+		}
+	}
 	if httpErr, ok := err.(*gocbcore.HTTPError); ok {
 		return &HTTPError{
 			InnerError:    httpErr.InnerError,