text: /* globals catcher, log */
  
  "use strict";
  
  this.communication = (function() {
    const exports = {};
  
    const registeredFunctions = {};
  
    exports.onMessage = catcher.watchFunction((req, sender, sendResponse) => {
      if (!(req.funcName in registeredFunctions)) {
        log.error(`Received unknown internal message type ${req.funcName}`);
        sendResponse({type: "error", name: "Unknown message type"});
        return;
      }
      if (!Array.isArray(req.args)) {
        log.error("Received message with no .args list");
        sendResponse({type: "error", name: "No .args"});
        return;
      }
      const func = registeredFunctions[req.funcName];
      let result;
      try {
        req.args.unshift(sender);
        result = func.apply(null, req.args);
      } catch (e) {
        log.error(`Error in ${req.funcName}:`, e, e.stack);
        // FIXME: should consider using makeError from catcher here:
        sendResponse({type: "error", message: e + "", errorCode: e.errorCode, popupMessage: e.popupMessage});
        return;
      }
      if (result && result.then) {
        result.then((concreteResult) => {
          sendResponse({type: "success", value: concreteResult});
        }).catch((errorResult) => {
          log.error(`Promise error in ${req.funcName}:`, errorResult, errorResult && errorResult.stack);
          sendResponse({type: "error", message: errorResult + "", errorCode: errorResult.errorCode, popupMessage: errorResult.popupMessage});
        });
        return;
      }
      sendResponse({type: "success", value: result});
    });
  
    exports.register = function(name, func) {
      registeredFunctions[name] = func;
    };
  
    return exports;
  })();
  