remove devAsserts that duplicate TS types

see graphql#3642

Author: yaacovCR

src/type/definition.ts

@@ -943,32 +943,20 @@ export class GraphQLField<
     config: GraphQLFieldConfig<TSource, TContext, TArgs>,
   ) {
     const coordinate = `${parentCoordinate}.${name}`;
-
-    devAssert(
-      isPlainObj(config),
-      `${coordinate} field config must be an object.`,
-    );
-
-    devAssert(
-      config.resolve == null || typeof config.resolve === 'function',
-      `${coordinate} field resolver must be a function if ` +
-        `provided, but got: ${inspect(config.resolve)}.`,
-    );
-
-    const argsConfig = config.args ?? {};
-    devAssert(
-      isPlainObj(argsConfig),
-      `${coordinate} args must be an object with argument names as keys.`,
-    );
-
     super(coordinate);
+
     this.name = assertName(name);
     this.description = config.description;
     this.type = config.type;
-    this.args = Object.entries(argsConfig).map(
-      ([argName, argConfig]) =>
-        new GraphQLArgument(coordinate, argName, argConfig),
-    );
+
+    const argsConfig = config.args;
+    this.args = argsConfig
+      ? Object.entries(argsConfig).map(
+          ([argName, argConfig]) =>
+            new GraphQLArgument(coordinate, argName, argConfig),
+        )
+      : [];
+
     this.resolve = config.resolve;
     this.subscribe = config.subscribe;
     this.deprecationReason = config.deprecationReason;