Merge branch 'bug0531' into test

src/components/knowledgeExtra/AddDevKnow.vue

@@ -400,7 +400,7 @@ export default {
                     return {
                       title: it.title,
                       position: it.contentType?it.contentType.split(","):[],
-                      content: it.content.replace(
+                      content: it.content && it.content.replace(
                         /{imageUrlPrefix}/g,
                         config.imgHost
                       ),