js: Error handling for browser errors

--

* Connection.js
  - Add some meaningful nativeMessaging feedback for failing
    communication due to misconfiguration or other browser-originated
    fails
  - add an "isDisconnected" property
  - "isNativeHostUnknown" tries to match browser's feedback string if
    the browser does not find gpgme-json
* init.js
  - initialization will now reject with a more meaningful error if the
    configuration is not set up or other browser-based errors
    (chrome.runtime.lastError) are present. This should speed up
    the normal initialization (not having to waiting for a timeout
    any more in case of improper setup)
* errors.js
  - CONN_NATIVEMESSAGE: New error that passes the browser's
    nativeMessaging error
  - CONN_NO_CONFIG: native messaging error indicating that the
    nativeMessaging host was not set up properly
* unittests.js:
  - added the "isDisconnected" property to the startup tests
  - added tests for proper behavior of connection checks

1 files changed, 10 insertions, 2 deletions

diff --git a/lang/js/src/Errors.js b/lang/js/src/Errors.js
index bf52cce7..6189414f 100644
--- a/lang/js/src/Errors.js
+++ b/lang/js/src/Errors.js
@@ -35,6 +35,14 @@ export const err_list = {
         msg: 'The nativeMessaging answer was empty.',
         type: 'error'
     },
+    'CONN_NO_CONFIG':{
+        msg: 'The browser does not recognize the nativeMessaging host.',
+        type: 'error'
+    },
+    'CONN_NATIVEMESSAGE':{
+        msg: 'The native messaging was not successful.',
+        type: 'error'
+    },
     'CONN_TIMEOUT': {
         msg: 'A connection timeout was exceeded.',
         type: 'error'
@@ -156,8 +164,8 @@ export function gpgme_error (code = 'GENERIC_ERROR', info){
  */
 class GPGME_Error extends Error{
     constructor (code = 'GENERIC_ERROR', msg=''){
-
-        if (code === 'GNUPG_ERROR' && typeof (msg) === 'string'){
+        const verboseErrors = ['GNUPG_ERROR', 'CONN_NATIVEMESSAGE'];
+        if (verboseErrors.includes(code) && typeof (msg) === 'string'){
             super(msg);
         } else if (err_list.hasOwnProperty(code)){
             if (msg){