handler/PadMessageHandler.js: handleMessage() got the wrong padId for read only pads

This was almost guaranteed to be broken.
Found by the Typescript compiler when doing an experimental conversion.

src/node/handler/PadMessageHandler.js

@@ -287,7 +287,7 @@ exports.handleMessage = async function(client, message)
 
     if (padId.indexOf("r.") === 0) {
       // Pad is readOnly, first get the real Pad ID
-      padId = await readOnlyManager.getPadId(padID);
+      padId = await readOnlyManager.getPadId(padId);
     }
 
     let { accessStatus } = await securityManager.checkAccess(padId, auth.sessionID, auth.token, auth.password);