Dont generate switch for "never" error serializers

This updates the error handler generation to just throw if there are
no modeled errors. This avoids compile time errors when trying to
access the `name` attribute.

Author: JordonPhillips

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

@@ -182,14 +182,18 @@ private void writeErrorChecker() {
     private void writeErrorHandler() {
         writer.addImport("SerdeContext", null, "@aws-sdk/types");
         writer.openBlock("serializeError(error: $T, ctx: Omit<SerdeContext, 'endpoint'>): Promise<$T> {", "}",
-                errorsType, applicationProtocol.getResponseType(), () -> {
-            writer.openBlock("switch (error.name) {", "}", () -> {
-                for (ShapeId errorId : operation.getErrors()) {
-                    writeErrorHandlerCase(errorId);
+            errorsType, applicationProtocol.getResponseType(), () -> {
+                if (operation.getErrors().isEmpty()) {
+                    writer.write("throw error;");
+                } else {
+                    writer.openBlock("switch (error.name) {", "}", () -> {
+                        for (ShapeId errorId : operation.getErrors()) {
+                            writeErrorHandlerCase(errorId);
+                        }
+                        writer.openBlock("default: {", "}", () -> writer.write("throw error;"));
+                    });
                 }
-                writer.openBlock("default: {", "}", () -> writer.write("throw error;"));
             });
-        });
         writer.write("");
     }