fix "show changes" edit button breakage from r18194

diff --git a/includes/DifferenceEngine.php b/includes/DifferenceEngine.php
index 4dbe8b4..8f093ba 100644 (file)
--- a/includes/DifferenceEngine.php
+++ b/includes/DifferenceEngine.php
@@ -437,6 +437,9 @@ CONTROL;
         * If there are revisions between the ones being compared, return a note saying so.
         */
        function getMultiNotice() {
+               if ( !is_object($this->mOldRev) || !is_object($this->mNewRev) )
+                       return '';
+
                $oldid = $this->mOldRev->getId();
                $newid = $this->mNewRev->getId();
                if ( $oldid > $newid ) {