fix(dynamodb): ensure table is ready

Use the DescribeTable operation on a table to ensure that the table is ready.

dynamodb/dynamodb.extern.d.ts

@@ -17,6 +17,7 @@ export interface ClientConfig {
 export interface Client$Inflight {
   readonly createTable: (input: Readonly<any>) => Promise<Readonly<any>>;
   readonly deleteTable: (input: Readonly<any>) => Promise<Readonly<any>>;
+  readonly describeTable: (input: Readonly<any>) => Promise<Readonly<any>>;
   readonly updateTimeToLive: (input: Readonly<any>) => Promise<Readonly<any>>;
 }
 export interface Credentials {

dynamodb/dynamodb.sim.w

@@ -8,6 +8,7 @@ interface Client {
   inflight createTable(input: Json): Json;
   inflight deleteTable(input: Json): Json;
   inflight updateTimeToLive(input: Json): Json;
+  inflight describeTable(input: Json): Json;
 }
 
 class Util {
@@ -140,7 +141,7 @@ pub class Table_sim impl dynamodb_types.ITable {
       })();
 
       // delete the table if it already exists because we might be reusing the container
-      try { client.deleteTable({ TableName: tableName }); } 
+      try { client.deleteTable({ TableName: tableName }); }
       catch e { }
 
       util.waitUntil(() => {
@@ -167,6 +168,15 @@ pub class Table_sim impl dynamodb_types.ITable {
             });
           }
 
+          // Wait until we can describe the table. This is
+          // to ensure that the table is ready to be used.
+          util.waitUntil(() => {
+            client.describeTable({
+              TableName: tableName,
+            });
+            return true;
+          });
+
           state.set("tableName", tableName);
           return true;
         } catch error {