feat: actually work with different topicSeparators

src/commands/which.ts

@@ -6,8 +6,16 @@ export default class Which extends Command {
 
   async run(): Promise<void> {
     const {argv} = await this.parse(Which)
-    const cmd = this.config.findCommand(argv.join(this.config.topicSeparator), {must: true})
-    CliUx.ux.styledHeader(cmd.id)
+    let command = argv
+
+    if (argv.length === 1 && typeof argv[0] === 'string') {
+      // If this if statement is true then the command to find was passed in as a single string, e.g. `mycli which "my command"`
+      // So we must use the topicSeparator to split it into an array
+      command = argv[0].split(this.config.topicSeparator)
+    }
+
+    const cmd = this.config.findCommand(command.join(':'), {must: true})
+    CliUx.ux.styledHeader(command.join(this.config.topicSeparator))
     CliUx.ux.styledObject({
       plugin: cmd.pluginName,
     }, ['plugin'])