chore(codegen): use type symbol when writing structure member (#1795)

Author: kuhe

private/smithy-rpcv2-cbor/src/models/errors.ts

@@ -1,7 +1,7 @@
 // smithy-typescript generated code
 import type { ExceptionOptionType as __ExceptionOptionType } from "@smithy/smithy-client";
 
-import { ComplexNestedErrorData, ValidationExceptionField } from "./models_0";
+import { type ComplexNestedErrorData, ValidationExceptionField } from "./models_0";
 import { RpcV2ProtocolServiceException as __BaseException } from "./RpcV2ProtocolServiceException";
 
 /**

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/StructuredMemberWriter.java

@@ -109,8 +109,15 @@ void writeMembers(TypeScriptWriter writer, Shape shape) {
             if (optionalSuffix.equals("?")) {
                 typeSuffix = " | undefined"; // support exactOptionalPropertyTypes.
             }
-            writer.write("${L}${L}${L}: ${T}${L};", memberPrefix, memberName, optionalSuffix,
-                    symbolProvider.toSymbol(member), typeSuffix);
+            writer.write(
+                "${L}${L}${L}: ${T}${L};",
+                memberPrefix, memberName, optionalSuffix,
+                symbolProvider.toSymbol(member)
+                    .toBuilder()
+                    .putProperty("typeOnly", true)
+                    .build(),
+                typeSuffix
+            );
 
             if (wroteDocs && position < members.size() - 1) {
                 writer.write("");