diff --git a/src/query.ts b/src/query.ts
index 3b4346f..9f1f38f 100644
--- a/src/query.ts
+++ b/src/query.ts
@@ -1,6 +1,6 @@
 import { Argument, BadRequest, Field, InternalServerError, NotSupported, ObjectType, QueryRequest, QueryResponse, Type } from "@hasura/ndc-sdk-typescript"
 import { ByKeysFunction, ConnectorSchema, QueryFields, QueryFunction, RowFieldValue, schemaConstants } from "./schema-ndc";
-import { ifNotNull, isArray, mapObjectValues, unreachable } from "./util";
+import { ifNotNull, isArray, mapObjectValues, throwBadRequest, unreachable } from "./util";
 import { AttributeValue, BatchGetItemCommand, DynamoDBClient } from "@aws-sdk/client-dynamodb";
 import { DynamoAttributeType, DynamoType, ObjectNamedType, ScalarNamedType, ScalarType, determineNamedTypeKind } from "./schema-dynamo";
 import { fromBase64, toBase64 } from "@smithy/util-base64";
@@ -338,7 +338,8 @@ function mkNdcResponseRowFromDynamoResponseRow(dynamoResponseRow: Record<string,
       case "column":
         const attributeName = field.column;
         const attributeValue = dynamoResponseRow[attributeName] ?? { NULL: true };
-        return resolveTypedValueFromAttributeValue(attributeValue, tableRowType.fields[attributeName].type, objectTypes);
+        const attributeSchemaType = tableRowType.fields[attributeName]?.type ?? throwBadRequest(`Attribute '${attributeName}' not declared in table schema`);
+        return resolveTypedValueFromAttributeValue(attributeValue, attributeSchemaType, objectTypes);
       case "relationship":
         throw new NotSupported("Relationship fields are not supported");
       default:
diff --git a/src/schema-ndc.ts b/src/schema-ndc.ts
index 42ba260..99a24ad 100644
--- a/src/schema-ndc.ts
+++ b/src/schema-ndc.ts
@@ -2,7 +2,7 @@ import { ArgumentInfo, FunctionInfo, ObjectField, ObjectType, Query, SchemaRespo
 import { TableSchema, ScalarType, dynamoTypeToType, AttributeSchema, DynamoType, dynamoArrayTypes, scalarTypeToDynamoType, ScalarNamedType, ObjectNamedType, determineNamedTypeKind } from "./schema-dynamo";
 import { ConfigurationPath, ConfigurationRangeError, InvalidConfigurationError, ObjectTypes } from "./configuration";
 import { Err, Ok, Result } from "./result";
-import { unreachable } from "./util";
+import { findWithIndex, throwInternalServerError, unreachable } from "./util";
 
 export type ConnectorSchema = {
   schemaResponse: SchemaResponse,
@@ -49,9 +49,10 @@ export function createSchema(tableSchema: TableSchema[], objectTypes: ObjectType
   return createTableRowTypes(tableSchema, objectTypes)
     .bind(([tableRowTypeNames, tableRowTypes]) =>
       Result.traverseAndCollectErrors(
-        tableSchema.map((table, tableIndex) =>
-          createByKeysFunctionForTable(table, tableIndex, tableRowTypeNames[table.tableName], { ...objectTypes, ...tableRowTypes })
-        )
+        tableSchema.map((table, tableIndex) => {
+          const tableRowTypeName = tableRowTypeNames[table.tableName] ?? throwInternalServerError(`Table row type name not found: ${table.tableName}`);
+          return createByKeysFunctionForTable(table, tableIndex, tableRowTypeName, { ...objectTypes, ...tableRowTypes });
+        })
       )
       .bind(generatedFunctionDefinitions => {
         const functionDefinitions = combineGenerated(...generatedFunctionDefinitions);
@@ -162,36 +163,36 @@ function createTablePkObjectType(tableSchema: TableSchema, tableSchemaIndex: num
         : new Ok(tablePkObjectTypeName)
     );
 
-  const hashAttrIndex = tableSchema.attributeSchema.findIndex(attr => attr.name === tableSchema.keySchema.hashKeyAttributeName)
   const hashAttrField: Result<[{[k: string]: ObjectField}, KeySchema], ConfigurationRangeError[]> =
-    hashAttrIndex !== -1
-      ? attributeSchemaAsObjectField(tableSchema.attributeSchema[hashAttrIndex], true, tableSchemaIndex, hashAttrIndex, objectTypes)
+    findWithIndex(tableSchema.attributeSchema, attr => attr.name === tableSchema.keySchema.hashKeyAttributeName)
+      .mapErr(_ => [{
+        path: ["tables", tableSchemaIndex, "keySchema", "hashKeyAttributeName"],
+        message: `Cannot find an attribute schema defined for the specified hash key attribute '${tableSchema.keySchema.hashKeyAttributeName}'`
+      }])
+      .bind(([hashAttrSchema, hashAttrIndex]) =>
+        attributeSchemaAsObjectField(hashAttrSchema, true, tableSchemaIndex, hashAttrIndex, objectTypes)
           .map(([key, value]) => {
             const hashAttrField = {[key]: value};
-            const hashKeySchema = { attributeName: tableSchema.attributeSchema[hashAttrIndex].name, schemaType: value.type, dynamoType: tableSchema.attributeSchema[hashAttrIndex].dynamoType };
+            const hashKeySchema = { attributeName: tableSchema.attributeSchema[hashAttrIndex]!.name, schemaType: value.type, dynamoType: tableSchema.attributeSchema[hashAttrIndex]!.dynamoType };
             return [hashAttrField, hashKeySchema];
           })
-      : new Err([{
-          path: ["tables", tableSchemaIndex, "keySchema", "hashKeyAttributeName"],
-          message: `Cannot find an attribute schema defined for the specified hash key attribute '${tableSchema.keySchema.hashKeyAttributeName}'`
-        }]);
+      );
 
   const rangeAttrField: Result<[{[k: string]: ObjectField}, KeySchema | null], ConfigurationRangeError[]> =
     tableSchema.keySchema.rangeKeyAttributeName === null
       ? new Ok([{}, null])
-      : new Ok<number, ConfigurationRangeError[]>(tableSchema.attributeSchema.findIndex(attr => attr.name === tableSchema.keySchema.rangeKeyAttributeName))
-        .bind(rangeAttrIndex =>
-          rangeAttrIndex !== -1
-            ? attributeSchemaAsObjectField(tableSchema.attributeSchema[rangeAttrIndex], true, tableSchemaIndex, rangeAttrIndex, objectTypes)
-                .map(([key, value]) => {
-                  const rangeAttrField = {[key]: value};
-                  const rangeKeySchema = { attributeName: tableSchema.attributeSchema[rangeAttrIndex].name, schemaType: value.type, dynamoType: tableSchema.attributeSchema[rangeAttrIndex].dynamoType };
-                  return [rangeAttrField, rangeKeySchema];
-                })
-            : new Err([{
-                path: ["tables", tableSchemaIndex, "keySchema", "rangeKeyAttributeName"],
-                message: `Cannot find an attribute schema defined for the specified range key attribute '${tableSchema.keySchema.rangeKeyAttributeName}'`
-              }])
+      : findWithIndex(tableSchema.attributeSchema, attr => attr.name === tableSchema.keySchema.rangeKeyAttributeName)
+        .mapErr(_ => [{
+          path: ["tables", tableSchemaIndex, "keySchema", "rangeKeyAttributeName"],
+          message: `Cannot find an attribute schema defined for the specified range key attribute '${tableSchema.keySchema.rangeKeyAttributeName}'`
+        }])
+        .bind(([rangeAttrSchema, rangeAttrIndex]) =>
+          attributeSchemaAsObjectField(rangeAttrSchema, true, tableSchemaIndex, rangeAttrIndex, objectTypes)
+            .map(([key, value]) => {
+              const rangeAttrField = {[key]: value};
+              const rangeKeySchema = { attributeName: rangeAttrSchema.name, schemaType: value.type, dynamoType: rangeAttrSchema.dynamoType };
+              return [rangeAttrField, rangeKeySchema];
+            })
         );
 
   return Result.collectErrors3(tablePkObjectTypeName, hashAttrField, rangeAttrField)
@@ -254,7 +255,7 @@ function createByKeysFunctionForTable(tableSchema: TableSchema, tableSchemaIndex
             },
           },
           primaryKeySchema,
-          tableRowType: objectTypes[tableRowTypeName],
+          tableRowType: objectTypes[tableRowTypeName] ?? throwInternalServerError(`Expected table row ObjectType ${tableRowTypeName} not found`),
         },
         newObjectTypes: {
           [tablePkObjectTypeName]: tablePkObjectType
@@ -275,7 +276,7 @@ function validateTypeUsages(functionInfos: FunctionInfo[], allObjectTypes: Objec
       .flatMap<[string, ObjectType]>(usedType => {
         const underlyingType = getUnderlyingNamedType(usedType, []);
         return underlyingType.kind === "object"
-          ? [[underlyingType.name, allObjectTypes[underlyingType.name]]]
+          ? [[underlyingType.name, allObjectTypes[underlyingType.name] ?? throwInternalServerError<ObjectType>(`Could not find object type '${underlyingType.name}'`)]]
           : []
         });
 
@@ -304,7 +305,7 @@ function validateTypeUsages(functionInfos: FunctionInfo[], allObjectTypes: Objec
       fieldTypeValidationResults.oks
         .flatMap<[string, ObjectType]>(underlyingFieldType =>
           underlyingFieldType.kind === "object"
-            ? [[underlyingFieldType.name, allObjectTypes[underlyingFieldType.name]]]
+            ? [[underlyingFieldType.name, (allObjectTypes[underlyingFieldType.name] ?? throwInternalServerError<ObjectType>(`Could not find object type '${underlyingFieldType.name}'`))]]
             : []
           );
 
diff --git a/src/util.ts b/src/util.ts
index 7182226..f6a514d 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -1,3 +1,6 @@
+import { BadRequest, InternalServerError } from "@hasura/ndc-sdk-typescript";
+import { Err, Ok, Result } from "./result";
+
 export const unreachable = (x: never): never => { throw new Error(`Unreachable code reached! The types lied! 😭 Unexpected value: ${x}`) };
 
 export function isArray(x: unknown): x is unknown[] {
@@ -15,3 +18,20 @@ export function mapObjectValues<T, U>(obj: { [k: string]: T }, fn: (value: T, pr
 export function mapObjectValues<T, U>(obj: { [k: string]: T }, fn: (value: T, propertyName: string) => U): Record<string, U> {
   return Object.fromEntries(Object.entries(obj).map(([prop, val]) => [prop, fn(val, prop)]));
 }
+
+// Throws an internal server error. Useful for using after a short-circuiting ?? operator to eliminate null/undefined from the type
+export function throwInternalServerError<T>(...args: ConstructorParameters<typeof InternalServerError>): NonNullable<T> {
+  throw new InternalServerError(...args);
+}
+
+// Throws an bad request error. Useful for using after a short-circuiting ?? operator to eliminate null/undefined from the type
+export function throwBadRequest<T>(...args: ConstructorParameters<typeof BadRequest>): NonNullable<T> {
+  throw new BadRequest(...args);
+}
+
+export function findWithIndex<T>(array: T[], predicate: (value: T, index: number, obj: T[]) => boolean): Result<[T, number], undefined> {
+  const index = array.findIndex(predicate);
+  return index !== -1
+    ? new Ok([array[index]!, index])
+    : new Err(undefined);
+}
diff --git a/tsconfig.json b/tsconfig.json
index 8b5db51..60a9990 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,7 +1,8 @@
 {
   "extends": "@tsconfig/node18/tsconfig.json",
   "compilerOptions": {
-    "resolveJsonModule": true
+    "resolveJsonModule": true,
+    "noUncheckedIndexedAccess": true
   },
   "include": [
     "src/**/*.ts",