fixup bugs related to PMP

Closes #25, as "Explain how to send messages using a certain PMP" is now added to the progress list.

README.md

@@ -120,7 +120,9 @@ A simple and user-friendly Matrix client made with Flutter and a Gomuks backend.
     - [ ] Align your message bubbles to left or right
     - [ ] Show media by default
     - [ ] Dynamic Theming
+    - [ ] Personas
         - [ ] Setting per-message profiles for users (MSC4461)
+        - [ ] Explain how to send messages using a certain PMP
     - [ ] Devices
         - [ ] Viewing devices
         - [ ] Verifying devices

lib/widgets/chat_page/composer/chat_box.dart

@@ -62,12 +62,6 @@ class ChatBox extends HookConsumerWidget {
       fontWeight: FontWeight.bold,
     );
 
-    final canSendMessages = ref.watch(
-      PowerLevelController.provider(
-        PowerLevelConfig(eventType: "m.room.message"),
-      ),
-    );
-
     return Positioned(
       bottom: 0,
       left: 0,
@@ -92,7 +86,12 @@ class ChatBox extends HookConsumerWidget {
                 child: Row(
                   spacing: 8,
                   mainAxisAlignment: MainAxisAlignment.center,
-                  children: canSendMessages
+                  children:
+                      ref.watch(
+                        PowerLevelController.provider(
+                          PowerLevelConfig(eventType: "m.room.message"),
+                        ),
+                      )
                       ? [
                           EmojiPickerButton(
                             context: context,
@@ -101,7 +100,6 @@ class ChatBox extends HookConsumerWidget {
                           ),
                           PopupMenuButton(
                             tooltip: "Add media",
-                            enabled: canSendMessages,
                             itemBuilder: (context) => [
                               PopupMenuItem(
                                 child: ListTile(
@@ -145,7 +143,6 @@ class ChatBox extends HookConsumerWidget {
                                 "#": style,
                               },
                               builder: (context, key) => TextFormField(
-                                enabled: canSendMessages,
                                 maxLines: 12,
                                 minLines: 1,
                                 autofocus: true,
@@ -164,7 +161,7 @@ class ChatBox extends HookConsumerWidget {
                             ),
                           ),
                           IconButton(
-                            onPressed: !canSendMessages ? null : send,
+                            onPressed: send,
                             icon: Icon(Icons.send),
                             tooltip: "Send message",
                           ),

lib/widgets/chat_page/room_chat.dart

@@ -365,13 +365,15 @@ class RoomChat extends HookConsumerWidget {
                                     text, {
                                     required shouldMention,
                                     required tags,
-                                  }) => notifier.send(
+                                  }) => notifier
+                                      .send(
                                         text,
                                         tags: tags,
                                         relationType: relationType.value,
                                         shouldMention: shouldMention,
                                         relation: relatedMessage.value,
-                                  ),
+                                      )
+                                      .onError(showError),
                               relationType: relationType.value,
                               relatedMessage: relatedMessage.value,
                               onDismiss: () => relatedMessage.value = null,