SPICE-HTML5: Improve error message

Current error message in SPICE-HTML5 error is poor (error-logging function
prints error.toString() which doesn't contain anything detailed).

This patch enhances this message in the following way:
 - error event contains target attribute ([1]),
 - the code in this patch checks for presence of 'url' attribute (which is
   contained in WebSocket object[2]). If the target contains url then
   meaningful message is logged.

[1]: https://developer.mozilla.org/en-US/docs/Web/API/Event
[2]: https://developer.mozilla.org/en-US/docs/Web/API/WebSocket

1 files changed, 3 insertions, 1 deletions

diff --git a/spiceconn.js b/spiceconn.js
index e33227e..ceebd5d 100644
--- a/spiceconn.js
+++ b/spiceconn.js
@@ -78,7 +78,9 @@ function SpiceConn(o)
         this.parent.state = "start";
     });
     this.ws.addEventListener('error', function(e) {
-        this.parent.log_err(">> WebSockets.onerror" + e.toString());
+        if ('url' in e.target) {
+            this.parent.log_err("WebSocket error: Can't connect to websocket on URL: " + e.target.url);
+        }
         this.parent.report_error(e);
     });
     this.ws.addEventListener('close', function(e) {