fix: populate parseBody() for errors or command responses

When preparing reponse body for command deserializers or error
deserializers, we don't always collect response body binaries
in structured JS object. If the command ouput or error has a
streaming trait, we need to keep the response body intact and
return users the raw response stream.

Author: AllanZhengYP

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/HttpBindingProtocolGenerator.java

@@ -19,16 +19,19 @@
 
 import java.util.Comparator;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import java.util.TreeMap;
 import java.util.TreeSet;
 import java.util.logging.Logger;
+
 import software.amazon.smithy.codegen.core.CodegenException;
 import software.amazon.smithy.codegen.core.Symbol;
 import software.amazon.smithy.codegen.core.SymbolProvider;
 import software.amazon.smithy.codegen.core.SymbolReference;
 import software.amazon.smithy.model.knowledge.HttpBinding;
 import software.amazon.smithy.model.knowledge.HttpBindingIndex;
+import software.amazon.smithy.model.knowledge.OperationIndex;
 import software.amazon.smithy.model.knowledge.TopDownIndex;
 import software.amazon.smithy.model.shapes.BlobShape;
 import software.amazon.smithy.model.shapes.BooleanShape;
@@ -662,11 +665,20 @@ private List<HttpBinding> readResponseBody(
         documentBindings.sort(Comparator.comparing(HttpBinding::getMemberName));
         List<HttpBinding> payloadBindings = bindingIndex.getResponseBindings(operationOrError, Location.PAYLOAD);
 
-        if (operationOrError.isOperationShape() && !payloadBindings.get(0).getMember().hasTrait(StreamingTrait.class)) {
-            writer.write("const data: any = await parseBody(output.body, context)");
-        } else {
-            // Don't collect stream for errors and streaming payload
+        // Prepare response body for deserializing.
+        OperationIndex operationIndex = context.getModel().getKnowledge(OperationIndex.class);
+        StructureShape operationOutputOrError = operationOrError.asStructureShape()
+                .orElseGet(() -> operationIndex.getOutput(operationOrError).orElse(null));
+        boolean hasStreamingComponent = Optional.ofNullable(operationOutputOrError)
+                .map(structure -> structure.getAllMembers().values().stream()
+                        .anyMatch(memberShape -> memberShape.hasTrait(StreamingTrait.class)))
+                .orElse(false);
+        if (hasStreamingComponent) {
+            // For operations with streaming output or errors with streaming body we keep the body intact.
             writer.write("const data: any = output.body;");
+        } else {
+            // Otherwise, we collect the response body to structured object with parseBody().
+            writer.write("const data: any = await parseBody(output.body, context);");
         }
 
         if (!documentBindings.isEmpty()) {