Added error handling in yang_path_arg triggered by no filter in get paginated

Fixed cornercase of restconf error return when no body
Fixed cornercase when exactly / given as xpath
Better error message when YANG not found: added which YANG file imports it

apps/backend/backend_get.c

@@ -467,7 +467,7 @@ get_list_pagination(clicon_handle        h,
 #endif
 
     /* Check if list/leaf-list */
-    if (yang_path_arg(yspec, xpath, &ylist) < 0)
+    if (yang_path_arg(yspec, xpath?xpath:"/", &ylist) < 0)
 	goto done;
     if (ylist == NULL){
 	if ((cbmsg = cbuf_new()) == NULL){

apps/backend/clixon_backend_plugin.h

@@ -84,7 +84,7 @@ typedef struct {
 */
 typedef struct {
     uint32_t          pd_offset;    /* Start of pagination interval */
-    uint32_t          pd_limit;     /* Number of elemenents (limit) */
+    uint32_t          pd_limit;     /* Number of elements (limit) */
     int               pd_locked;    /* Running datastore is locked by this caller */
     cxobj            *pd_xstate;    /* Returned xml state tree */
 } pagination_data_t;

apps/backend/clixon_backend_transaction.c

@@ -286,7 +286,6 @@ transaction_log(clicon_handle      h,
     return 0;
 }
 
-
 /*! Get pagination data: offset parameter
  *
  * @param[in]  pd     Pagination userdata