Fix #2861: Check error body before dereference

Not a perfect solution, and I certainly have no business editing this code.
But I do want to get AWS's attention to get this fixed.

Author: Brian Crowell

codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/AwsEc2.java

@@ -97,9 +97,13 @@ public void generateSharedComponents(GenerationContext context) {
                        + "  output: $T,\n"
                        + "  data: any\n"
                        + "): string => {", "};", responseType, () -> {
+            // Default a 503 status code to the Unavailable code.
+            writer.openBlock("if (output.statusCode == 503) {", "}", () -> writer.write("return 'Unavailable';"));
+
             // Attempt to fetch the error code from the specific location.
-            String errorCodeLocation = getErrorBodyLocation(context, "data") + ".Code";
-            writer.openBlock("if ($L !== undefined) {", "}", errorCodeLocation, () -> {
+            String errorBodyLocation = getErrorBodyLocation(context, "data");
+            String errorCodeLocation = errorBodyLocation + ".Code";
+            writer.openBlock("if ($L !== undefined && $L !== undefined) {", "}", errorBodyLocation, errorCodeLocation, () -> {
                 writer.write("return $L;", errorCodeLocation);
             });
 

codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/AwsQuery.java

@@ -97,9 +97,13 @@ public void generateSharedComponents(GenerationContext context) {
                        + "  output: $T,\n"
                        + "  data: any\n"
                        + "): string => {", "};", responseType, () -> {
+            // Default a 503 status code to the Unavailable code.
+            writer.openBlock("if (output.statusCode == 503) {", "}", () -> writer.write("return 'Unavailable';"));
+
             // Attempt to fetch the error code from the specific location.
-            String errorCodeLocation = getErrorBodyLocation(context, "data") + ".Code";
-            writer.openBlock("if ($L !== undefined) {", "}", errorCodeLocation, () -> {
+            String errorBodyLocation = getErrorBodyLocation(context, "data");
+            String errorCodeLocation = errorBodyLocation + ".Code";
+            writer.openBlock("if ($L !== undefined && $L !== undefined) {", "}", errorBodyLocation, errorCodeLocation, () -> {
                 writer.write("return $L;", errorCodeLocation);
             });
 

codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/AwsRestXml.java

@@ -110,9 +110,13 @@ public void generateSharedComponents(GenerationContext context) {
                        + "  output: $T,\n"
                        + "  data: any\n"
                        + "): string => {", "};", responseType, () -> {
+            // Default a 503 status code to the Unavailable code.
+            writer.openBlock("if (output.statusCode == 503) {", "}", () -> writer.write("return 'Unavailable';"));
+
             // Attempt to fetch the error code from the specific location.
-            String errorCodeLocation = getErrorBodyLocation(context, "data") + ".Code";
-            writer.openBlock("if ($L !== undefined) {", "}", errorCodeLocation, () -> {
+            String errorBodyLocation = getErrorBodyLocation(context, "data");
+            String errorCodeLocation = errorBodyLocation + ".Code";
+            writer.openBlock("if ($L !== undefined && $L !== undefined) {", "}", errorBodyLocation, errorCodeLocation, () -> {
                 writer.write("return $L;", errorCodeLocation);
             });