Fixed crash issue when no callid is given.

changecall.lua

@@ -25,7 +25,7 @@
 
 _addon.author   = 'atom0s';
 _addon.name     = 'ChangeCall';
-_addon.version  = '1.0.0';
+_addon.version  = '1.0.1';
 
 require 'common'
 
@@ -47,7 +47,12 @@ ashita.register_event('command', function(command, ntype)
     end
     
     -- Pull the new call id to use..
-    settings.callid = tonumber(string.gsub(command, '/changecall', ''):trim());
+    local callid = string.gsub(command, '/changecall', ''):trim();
+    if (callid == nil or string.len(callid) == 0) then
+        settings.callid = 0;
+    else
+        settings.callid = tonumber(callid);
+    end
     
     local newid = '';
     if (settings.callid > 0) then