Fixed null parameter handling

Default to STRING type for null parameters without explicit type

Check member.DeclaringType instead of instance.Type to handle SqlQuery<string> scenarios where the instance type doesn't exactly match typeof(string)

Author: dovydasm

src/Ivy.Data.BigQuery/BigQueryParameter.cs

@@ -284,8 +284,15 @@ internal Google.Cloud.BigQuery.V2.BigQueryParameter ToBigQueryParameter()
                 {
                     throw new InvalidOperationException($"Cannot automatically determine BigQuery array type for parameter '{ParameterName}'. Set the BigQueryDbType explicitly (e.g., BigQueryDbType.Array with element type).");
                 }
-
-                throw new InvalidOperationException($"Cannot determine BigQueryDbType for parameter '{ParameterName}'. Set DbType or BigQueryDbType explicitly.");
+                
+                if (Value == null || Value == DBNull.Value)
+                {
+                    type = Google.Cloud.BigQuery.V2.BigQueryDbType.String;
+                }
+                else
+                {
+                    throw new InvalidOperationException($"Cannot determine BigQueryDbType for parameter '{ParameterName}'. Set DbType or BigQueryDbType explicitly.");
+                }
             }
 
             var name = ParameterName[1..];

src/Ivy.EFCore.BigQuery/Query/Internal/BigQueryStringMemberTranslator.cs

@@ -13,9 +13,6 @@ public class BigQueryStringMemberTranslator : IMemberTranslator
 {
     private readonly ISqlExpressionFactory _sqlExpressionFactory;
 
-    private static readonly MemberInfo StringLength
-        = typeof(string).GetProperty(nameof(string.Length))!;
-
     public BigQueryStringMemberTranslator(ISqlExpressionFactory sqlExpressionFactory)
     {
         _sqlExpressionFactory = sqlExpressionFactory;
@@ -27,7 +24,7 @@ public BigQueryStringMemberTranslator(ISqlExpressionFactory sqlExpressionFactory
         Type returnType,
         IDiagnosticsLogger<DbLoggerCategory.Query> logger)
     {
-        if (member == StringLength && instance?.Type == typeof(string))
+        if (member.Name == nameof(string.Length) && member.DeclaringType == typeof(string) && instance is not null)
         {
             return _sqlExpressionFactory.Function(
                 "LENGTH",