copilot chat: Remove invalid assertions (#32977)

Bennet Bo Fenner created 5 months ago

Related to #32888, but will not fix the issue. 
Turns out these assertions are wrong (Not sure if they were correct at
some point).
I tested with this code:
```
        request = LanguageModelRequest {
            messages: vec![
                LanguageModelRequestMessage {
                    role: Role::User,
                    content: vec![MessageContent::Text("Give me 10 jokes".to_string())],
                    cache: false,
                },
                LanguageModelRequestMessage {
                    role: Role::Assistant,
                    content: vec![MessageContent::Text("Sure, here are 10 jokes:".to_string())],
                    cache: false,
                },
            ],
            ..request
        };
```
The API happily accepted this and Claude proceeded to tell me 10 jokes.

Release Notes:

- N/A

Change summary

crates/language_models/src/provider/copilot_chat.rs | 17 ---------------
1 file changed, 17 deletions(-)

Detailed changes

crates/language_models/src/provider/copilot_chat.rs

@@ -267,23 +267,6 @@ impl LanguageModel for CopilotChatLanguageModel {
             LanguageModelCompletionError,
         >,
     > {
-        if let Some(message) = request.messages.last() {
-            if message.contents_empty() {
-                const EMPTY_PROMPT_MSG: &str =
-                    "Empty prompts aren't allowed. Please provide a non-empty prompt.";
-                return futures::future::ready(Err(anyhow::anyhow!(EMPTY_PROMPT_MSG).into()))
-                    .boxed();
-            }
-
-            // Copilot Chat has a restriction that the final message must be from the user.
-            // While their API does return an error message for this, we can catch it earlier
-            // and provide a more helpful error message.
-            if !matches!(message.role, Role::User) {
-                const USER_ROLE_MSG: &str = "The final message must be from the user. To provide a system prompt, you must provide the system prompt followed by a user prompt.";
-                return futures::future::ready(Err(anyhow::anyhow!(USER_ROLE_MSG).into())).boxed();
-            }
-        }
-
         let copilot_request = match into_copilot_chat(&self.model, request) {
             Ok(request) => request,
             Err(err) => return futures::future::ready(Err(err.into())).boxed(),