Use const instead of let when possible

src/gui/Popups/InviteToRoomPopup.qml

@@ -87,7 +87,7 @@ BoxPopup {
             // TODO: handle these: real user not found
             const lines = []
 
-            for (let [user, error] of failedInvites) {
+            for (const [user, error] of failedInvites) {
                 const type = py.getattr(
                     py.getattr(error, "__class__"), "__name__",
                 )

src/gui/Popups/PasswordPopup.qml

@@ -35,7 +35,7 @@ BoxPopup {
 
     box.buttonCallbacks: ({
         ok: button => {
-            let password      = passwordField.text
+            const password    = passwordField.text
             okClicked         = true
             button.loading    = true
             errorMessage.text = ""