fix: Invalid date query parameter on email failures endpoint fails with 500 #299

src/main/java/com/sivalabs/ft/features/api/GlobalExceptionHandler.java

@@ -10,6 +10,7 @@
 import org.springframework.http.ProblemDetail;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
+import org.springframework.web.method.annotation.MethodArgumentTypeMismatchException;
 
 @RestControllerAdvice
 class GlobalExceptionHandler {
@@ -42,4 +43,14 @@ ProblemDetail handle(BadRequestException e) {
         problemDetail.setProperty("timestamp", Instant.now());
         return problemDetail;
     }
+
+    @ExceptionHandler(MethodArgumentTypeMismatchException.class)
+    ProblemDetail handle(MethodArgumentTypeMismatchException e) {
+        log.error("Bad Request", e);
+        ProblemDetail problemDetail = ProblemDetail.forStatusAndDetail(
+                BAD_REQUEST, "Invalid value for request parameter '" + e.getName() + "'");
+        problemDetail.setTitle("Bad Request");
+        problemDetail.setProperty("timestamp", Instant.now());
+        return problemDetail;
+    }
 }

src/main/java/com/sivalabs/ft/features/api/controllers/EmailDeliveryFailureController.java

@@ -37,6 +37,7 @@ class EmailDeliveryFailureController {
             responses = {
                 @ApiResponse(responseCode = "200", description = "Successful response"),
                 @ApiResponse(responseCode = "401", description = "Unauthorized"),
+                @ApiResponse(responseCode = "400", description = "Invalid date format"),
                 @ApiResponse(responseCode = "403", description = "Forbidden - ADMIN role required")
             })
     ResponseEntity<Page<EmailDeliveryFailureDto>> getFailures(

src/test/java/com/sivalabs/ft/features/api/controllers/EmailDeliveryFailureAdminApiTest.java

@@ -15,6 +15,8 @@
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.HttpStatus;
 import org.springframework.jdbc.core.JdbcTemplate;
@@ -171,6 +173,18 @@ INSERT INTO email_delivery_failures (id, notification_id, recipient_email, event
         assertThat(content.get(0).get("recipientEmail")).isEqualTo("user1@example.com");
     }
 
+    @ParameterizedTest(name = "should reject malformed date query param: {0}")
+    @ValueSource(strings = {"invalid-date", "2026-13-01", "2026-02-30", "2026/01/12", "2026-01-12T00:00:00Z"})
+    @WithMockOAuth2User(
+            username = "admin",
+            roles = {"ADMIN"})
+    void shouldReturn400ForInvalidDateFormat(String invalidDate) throws Exception {
+        var response =
+                mvc.get().uri("/api/admin/email-failures?date=" + invalidDate).exchange();
+
+        assertThat(response).hasStatus(HttpStatus.BAD_REQUEST);
+    }
+
     // ========== GET /api/admin/email-failures/{id} ==========
 
     @Test