[OPIK-853] handle gemini client errors

apps/opik-backend/src/main/java/com/comet/opik/domain/llm/LlmProviderService.java

@@ -22,5 +22,5 @@ void generateStream(
 
     void validateRequest(@NonNull ChatCompletionRequest request);
 
-    Optional<ErrorMessage> getLlmProviderError(@NonNull Throwable runtimeException);
+    Optional<ErrorMessage> getLlmProviderError(@NonNull Throwable throwable);
 }

apps/opik-backend/src/main/java/com/comet/opik/infrastructure/llm/antropic/LlmProviderAnthropic.java

@@ -57,8 +57,8 @@ public void validateRequest(@NonNull ChatCompletionRequest request) {
     }
 
     @Override
-    public Optional<ErrorMessage> getLlmProviderError(@NonNull Throwable runtimeException) {
-        if (runtimeException instanceof AnthropicHttpException anthropicHttpException) {
+    public Optional<ErrorMessage> getLlmProviderError(@NonNull Throwable throwable) {
+        if (throwable instanceof AnthropicHttpException anthropicHttpException) {
             return Optional.of(new ErrorMessage(anthropicHttpException.statusCode(),
                     anthropicHttpException.getMessage()));
         }

apps/opik-backend/src/main/java/com/comet/opik/infrastructure/llm/gemini/GeminiErrorObject.java

@@ -0,0 +1,18 @@
+package com.comet.opik.infrastructure.llm.gemini;
+
+import io.dropwizard.jersey.errors.ErrorMessage;
+
+import java.util.Optional;
+
+public record GeminiErrorObject(GeminiError error) {
+    public Optional<ErrorMessage> toErrorMessage() {
+        if (error != null) {
+            return Optional.of(new ErrorMessage(error.code(), error.message(), error().status()));
+        }
+
+        return Optional.empty();
+    }
+}
+
+record GeminiError(int code, String message, String status) {
+}

apps/opik-backend/src/main/java/com/comet/opik/infrastructure/llm/gemini/LlmProviderGemini.java

@@ -2,16 +2,20 @@
 
 import com.comet.opik.api.ChunkedResponseHandler;
 import com.comet.opik.domain.llm.LlmProviderService;
+import com.comet.opik.utils.JsonUtils;
 import dev.ai4j.openai4j.chat.ChatCompletionRequest;
 import dev.ai4j.openai4j.chat.ChatCompletionResponse;
 import io.dropwizard.jersey.errors.ErrorMessage;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 
+import java.io.UncheckedIOException;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Consumer;
 
+@Slf4j
 @RequiredArgsConstructor
 public class LlmProviderGemini implements LlmProviderService {
     private final @NonNull GeminiClientGenerator llmProviderClientGenerator;
@@ -39,9 +43,31 @@ public void generateStream(@NonNull ChatCompletionRequest request, @NonNull Stri
     public void validateRequest(@NonNull ChatCompletionRequest request) {
     }
 
+    /// gemini throws RuntimeExceptions with message structure as follows:
+    /// ```
+    /// java.lang.RuntimeException: HTTP error (429): {
+    ///   "error": {
+    ///     "code": 429,
+    ///     "message": "Resource has been exhausted (e.g. check quota).",
+    ///     "status": "RESOURCE_EXHAUSTED"
+    ///   }
+    /// }
+    ///  ```
     @Override
-    public Optional<ErrorMessage> getLlmProviderError(@NonNull Throwable runtimeException) {
+    public Optional<ErrorMessage> getLlmProviderError(@NonNull Throwable throwable) {
+        String message = throwable.getMessage();
+        var openBraceIndex = message.indexOf('{');
+        if (openBraceIndex >= 0) {
+            String jsonPart = message.substring(openBraceIndex); // Extract JSON part
+            try {
+                var geminiError = JsonUtils.readValue(jsonPart, GeminiErrorObject.class);
+                return geminiError.toErrorMessage();
+            } catch (UncheckedIOException e) {
+                log.warn("failed to parse Gemini error message", e);
+                return Optional.empty();
+            }
+        }
+
         return Optional.empty();
     }
-
 }

apps/opik-backend/src/main/java/com/comet/opik/infrastructure/llm/openai/LlmProviderOpenAi.java

@@ -43,8 +43,8 @@ public void validateRequest(@NonNull ChatCompletionRequest request) {
     }
 
     @Override
-    public Optional<ErrorMessage> getLlmProviderError(@NonNull Throwable runtimeException) {
-        if (runtimeException instanceof OpenAiHttpException openAiHttpException) {
+    public Optional<ErrorMessage> getLlmProviderError(@NonNull Throwable throwable) {
+        if (throwable instanceof OpenAiHttpException openAiHttpException) {
             return Optional.of(new ErrorMessage(openAiHttpException.code(), openAiHttpException.getMessage()));
         }