Fix OpenAI finish_reason values when empty (ollama#4368)

Author: jmorganca

openai/openai.go

@@ -107,9 +107,14 @@ func toChatCompletion(id string, r api.ChatResponse) ChatCompletion {
 		Model:             r.Model,
 		SystemFingerprint: "fp_ollama",
 		Choices: []Choice{{
-			Index:        0,
-			Message:      Message{Role: r.Message.Role, Content: r.Message.Content},
-			FinishReason: &r.DoneReason,
+			Index:   0,
+			Message: Message{Role: r.Message.Role, Content: r.Message.Content},
+			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{
-			{
-				Index:        0,
-				Delta:        Message{Role: "assistant", Content: r.Message.Content},
-				FinishReason: &r.DoneReason,
-			},
-		},
+		Choices: []ChunkChoice{{
+			Index: 0,
+			Delta: Message{Role: "assistant", Content: r.Message.Content},
+			FinishReason: func(reason string) *string {
+				if len(reason) > 0 {
+					return &reason
+				}
+				return nil
+			}(r.DoneReason),
+		}},
 	}
 }