check if content isn't just whitespaces (client side this time)

Signed-off-by: carsand101 <carsand101@noreply.codeberg.org>

static/js/chat.js

@@ -72,10 +72,15 @@ async function sendMessage(content, id) {
 
 messageBox.addEventListener("keyup", function onEvent(event) {
     if (event.key === "Enter") {
+        if (!messageBox.value.trim().length == 0) {
             sendMessage(messageBox.value, channelID)
             updateMessages(channelID)
             messageBox.value = ""
         }
+        else {
+            return;
+        }
+    }
 })
 
 function update() {