feat(smithy-client): add ExceptionOptionType type (#3314)

packages/smithy-client/src/exceptions.ts

@@ -1,5 +1,16 @@
 import { HttpResponse, MetadataBearer, ResponseMetadata, RetryableTrait, SmithyException } from "@aws-sdk/types";
 
+/**
+ * The type of the exception class constructor parameter. The returned type contains the properties
+ * in the `ExceptionType` but not in the `BaseExceptionType`. If the `BaseExceptionType` contains
+ * `$metadata` property, it's also included in the returned type.
+ * @internal
+ */
+export type ExceptionOptionType<ExceptionType extends Error, BaseExceptionType extends Error> = Omit<
+  ExceptionType,
+  Exclude<keyof BaseExceptionType, "$metadata">
+>;
+
 export interface ServiceExceptionOptions extends SmithyException, MetadataBearer {
   message?: string;
 }