     # initialization, and also if we disconnect and reconnect.
     _update_all: (v) =>
         #console.log("_update_all(#{@_table})", v)
+        if not v?
+            console.warn("_update_all(#{@_table}) called with v=undefined")
+            return
 
         # Restructure the array of records in v as a mapping from the primary key
         # to the corresponding record.

                #console.log("query #{@_table}: -- got result of doing query", resp)
                if first
                    first = false
                    if err
                        console.warn("query #{@_table}: _run: first error ", err)
                        cb?(err)
                    else


    _update_change: (change) =>
        #console.log("_update_change", change)
        if not @_value_local?
            console.warn("BUG: tried to call _update_change even though local not yet defined")
            return
        changed_keys = []
        conflict = false
        if change.new_val?
