feat(codegen): reject null in non-sparse collections (#2771)

This updates list parsing for SSDKs to throw an error whenever a
null value shows up in a list or set that isn't meant to be sparse.

Clients remain tolerant of these nulls to preserve compatibility with
services that are not so strict.

Author: JordonPhillips

Diff for: codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/AwsProtocolUtils.java

@@ -330,10 +330,6 @@ private static boolean filterMalformedRequestTests(
         if (testCase.getId().startsWith("RestJsonMalformedUnion")) {
             return true;
         }
-        //TODO: we don't do any list validation
-        if (testCase.getId().startsWith("RestJsonBodyMalformedList")) {
-            return true;
-        }
         //TODO: we don't validate map values
         if (testCase.getId().equals("RestJsonBodyMalformedMapNullValue")) {
             return true;

Diff for: codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/JsonShapeDeserVisitor.java

@@ -32,6 +32,7 @@
 import software.amazon.smithy.model.traits.SparseTrait;
 import software.amazon.smithy.model.traits.TimestampFormatTrait.Format;
 import software.amazon.smithy.typescript.codegen.CodegenUtils;
+import software.amazon.smithy.typescript.codegen.TypeScriptSettings.ArtifactType;
 import software.amazon.smithy.typescript.codegen.TypeScriptWriter;
 import software.amazon.smithy.typescript.codegen.integration.DocumentMemberDeserVisitor;
 import software.amazon.smithy.typescript.codegen.integration.DocumentShapeDeserVisitor;
@@ -62,10 +63,11 @@ private DocumentMemberDeserVisitor getMemberVisitor(MemberShape memberShape, Str
     protected void deserializeCollection(GenerationContext context, CollectionShape shape) {
         TypeScriptWriter writer = context.getWriter();
         Shape target = context.getModel().expectShape(shape.getMember().getTarget());
+        ArtifactType artifactType = context.getSettings().getArtifactType();
 
         // Filter out null entries if we don't have the sparse trait.
         String potentialFilter = "";
-        if (!shape.hasTrait(SparseTrait.ID)) {
+        if (!shape.hasTrait(SparseTrait.ID) && !artifactType.equals(ArtifactType.SSDK)) {
             potentialFilter = ".filter((e: any) => e != null)";
         }
 
@@ -75,7 +77,15 @@ protected void deserializeCollection(GenerationContext context, CollectionShape
 
         writer.openBlock("return (output || [])$L.map((entry: any) => {", "});", potentialFilter, () -> {
             // Short circuit null values from serialization.
-            writer.write("if (entry === null) { return null as any; }");
+            writer.openBlock("if (entry === null) {", "}", () -> {
+                // In the SSDK we want to be very strict about not accepting nulls in non-sparse lists.
+                if (!shape.hasTrait(SparseTrait.ID) && artifactType.equals(ArtifactType.SSDK)) {
+                    writer.write("throw new TypeError('All elements of the non-sparse list $S must be non-null.');",
+                                 shape.getId());
+                } else {
+                    writer.write("return null as any;");
+                }
+            });
 
             if (shape.isSetShape()) {
                 writer.write("const parsedEntry = $L$L;",