Sanitize 400 error messages in GlobalExceptionHandler and validation filters to use static strings. This change improves consistency and prevents leaking internal exception details. Updated tests to reflect new error messages for JSON parsing and bad request scenarios.

SatelliteProvider.Api/Validators/UavUploadValidationFilter.cs

@@ -31,6 +31,7 @@ public sealed class UavUploadValidationFilter : IEndpointFilter
     private const string MetadataKeyPrefix = "metadata.";
     private const string MetadataField = "metadata";
     private const string FilesField = "files";
+    private const string MetadataJsonParseError = "`metadata` could not be parsed as JSON.";
 
     private readonly IValidator<UavTileBatchMetadataPayload> _validator;
     private readonly JsonSerializerOptions _jsonOptions;
@@ -72,14 +73,11 @@ public sealed class UavUploadValidationFilter : IEndpointFilter
         {
             payload = JsonSerializer.Deserialize<UavTileBatchMetadataPayload>(metadataField, _jsonOptions);
         }
-        catch (JsonException ex)
+        catch (JsonException)
         {
-            // System.Text.Json with UnmappedMemberHandling.Disallow + [JsonRequired]
-            // covers: unknown root/nested fields, missing required fields, type
-            // mismatches. Surface uniformly as `errors.metadata`.
             return Results.ValidationProblem(new Dictionary<string, string[]>
             {
-                [MetadataField] = new[] { $"`metadata` could not be parsed as JSON: {ex.Message}" },
+                [MetadataField] = new[] { MetadataJsonParseError },
             });
         }