Fix case-sensitivity of /me to match rest of slash commands

also better error handling for attempted runs of unimplemented commands

src/SlashCommands.tsx

@@ -118,7 +118,7 @@ export class Command {
 
     run(roomId: string, args: string, cmd: string) {
         // if it has no runFn then its an ignored/nop command (autocomplete only) e.g `/me`
-        if (!this.runFn) return;
+        if (!this.runFn) return reject(_t("Command error"));
         return this.runFn.bind(this)(roomId, args, cmd);
     }
 

src/editor/serialize.ts

@@ -62,16 +62,20 @@ export function textSerialize(model: EditorModel) {
 }
 
 export function containsEmote(model: EditorModel) {
-    return startsWith(model, "/me ");
+    return startsWith(model, "/me ", true);
 }
 
-export function startsWith(model: EditorModel, prefix: string) {
+export function startsWith(model: EditorModel, prefix: string, caseInsensitive = false) {
     const firstPart = model.parts[0];
     // part type will be "plain" while editing,
     // and "command" while composing a message.
-    return firstPart &&
-        (firstPart.type === "plain" || firstPart.type === "command") &&
-        firstPart.text.startsWith(prefix);
+    let text = firstPart && firstPart.text;
+    if (caseInsensitive) {
+        prefix = prefix.toLowerCase();
+        text = text.toLowerCase();
+    }
+
+    return firstPart && (firstPart.type === "plain" || firstPart.type === "command") && text.startsWith(prefix);
 }
 
 export function stripEmoteCommand(model: EditorModel) {