language_models: Avoid debug formatting in Copilot Chat, OpenAI errors (#50824)

Tom Houlé created 

See these screenshots:

<img width="832" height="564" alt="image"
src="https://github.com/user-attachments/assets/64d04fe7-4be7-4fbf-8536-b4b7a2ea62ed"
/>

<img width="836" height="1094" alt="image"
src="https://github.com/user-attachments/assets/247b215c-8e7e-4eff-8e08-b1b9ee8894b9"
/>

Release Notes:

- Fixed some error messages in OpenAI/Copilot Chat conversations that
were using the Debug representation.

Change summary

crates/language_models/src/provider/copilot_chat.rs | 2 +-
crates/language_models/src/provider/open_ai.rs      | 6 +++---
2 files changed, 4 insertions(+), 4 deletions(-)

Detailed changes

crates/language_models/src/provider/copilot_chat.rs 🔗 

@@ -748,7 +748,7 @@ impl CopilotResponsesEventMapper {
             }
 
             copilot_responses::StreamEvent::GenericError { error } => vec![Err(
-                LanguageModelCompletionError::Other(anyhow!(format!("{error:?}"))),
+                LanguageModelCompletionError::Other(anyhow!(error.message)),
             )],
 
             copilot_responses::StreamEvent::Created { .. }

crates/language_models/src/provider/open_ai.rs 🔗 

@@ -1069,9 +1069,9 @@ impl OpenAiResponseEventMapper {
             }
             ResponsesStreamEvent::Error { error }
             | ResponsesStreamEvent::GenericError { error } => {
-                vec![Err(LanguageModelCompletionError::Other(anyhow!(format!(
-                    "{error:?}"
-                ))))]
+                vec![Err(LanguageModelCompletionError::Other(anyhow!(
+                    error.message
+                )))]
             }
             ResponsesStreamEvent::OutputTextDone { .. } => Vec::new(),
             ResponsesStreamEvent::OutputItemDone { .. }