Don't show errors on older versions of ThinBridge

We need this in order to work nicely on with older versions of
ThinBridge (in particular < v4.0.2.4).

Since the new "R edge" command is only available since v4.0.2.4,
we need to suppress "no-such-command" errors when older versions
are in use.

Signed-off-by: Fujimoto Seiji <fujimoto@ceptord.net>

webextension/edge/background.js

@@ -348,6 +348,11 @@ var ResourceCap = {
 	check: function(tabId, ntabs) {
 		var query = new String(`R ${BROWSER} ${ntabs}`);
 		chrome.runtime.sendNativeMessage(SERVER_NAME, query, (resp) => {
+			// Need this to support ThinBridge v4.0.2.3 (or before)
+			if (chrome.runtime.lastError) {
+				return;
+			}
+
 			if (resp.closeTab) {
 				chrome.tabs.remove(tabId, () => {
 					if (chrome.runtime.lastError) {