Fix OpenAI `finish_reason` values when empty (#4368)

openai/openai.go

@@ -109,7 +109,12 @@ func toChatCompletion(id string, r api.ChatResponse) ChatCompletion {
 		Choices: []Choice{{
 			Index:   0,
 			Message: Message{Role: r.Message.Role, Content: r.Message.Content},
-			FinishReason: &r.DoneReason,
+			FinishReason: func(reason string) *string {
+				if len(reason) > 0 {
+					return &reason
+				}
+				return nil
+			}(r.DoneReason),
 		}},
 		Usage: Usage{
 			// TODO: ollama returns 0 for prompt eval if the prompt was cached, but openai returns the actual count
@@ -127,13 +132,16 @@ func toChunk(id string, r api.ChatResponse) ChatCompletionChunk {
 		Created:           time.Now().Unix(),
 		Model:             r.Model,
 		SystemFingerprint: "fp_ollama",
-		Choices: []ChunkChoice{
-			{
+		Choices: []ChunkChoice{{
 			Index: 0,
 			Delta: Message{Role: "assistant", Content: r.Message.Content},
-				FinishReason: &r.DoneReason,
-			},
-		},
+			FinishReason: func(reason string) *string {
+				if len(reason) > 0 {
+					return &reason
+				}
+				return nil
+			}(r.DoneReason),
+		}},
 	}
 }