added back nil check for schema

Signed-off-by: James Humphries <james@james-humphries.co.uk>

internal/tofu/context_plugins.go

@@ -69,6 +69,9 @@ func (cp *contextPlugins) ResourceTypeSchema(ctx context.Context, providerAddr a
 	}
 
 	schema, version := providerSchema.SchemaForResourceType(resourceMode, resourceType)
+	if schema == nil {
+		return nil, 0, diags
+	}
 	return schema.Block, version, diags
 }