3 files changed, 17 insertions, 0 deletions
diff --git a/cli/js/errors.ts b/cli/js/errors.ts
index fc4021321..69afcf148 100644
--- a/cli/js/errors.ts
+++ b/cli/js/errors.ts
@@ -23,6 +23,7 @@ export enum ErrorKind {
   URIError = 20,
   TypeError = 21,
   Other = 22,
+  Busy = 23,
 }
 
 export function getErrorClass(kind: ErrorKind): { new (msg: string): Error } {
@@ -67,6 +68,8 @@ export function getErrorClass(kind: ErrorKind): { new (msg: string): Error } {
       return BadResource;
     case ErrorKind.Http:
       return Http;
+    case ErrorKind.Busy:
+      return Busy;
   }
 }
 
@@ -172,6 +175,12 @@ class Http extends Error {
     this.name = "Http";
   }
 }
+class Busy extends Error {
+  constructor(msg: string) {
+    super(msg);
+    this.name = "Busy";
+  }
+}
 
 export const errors = {
   NotFound: NotFound,
@@ -191,4 +200,5 @@ export const errors = {
   UnexpectedEof: UnexpectedEof,
   BadResource: BadResource,
   Http: Http,
+  Busy: Busy,
 };
diff --git a/cli/js/lib.deno.ns.d.ts b/cli/js/lib.deno.ns.d.ts
index 0ec27dbce..443952c96 100644
--- a/cli/js/lib.deno.ns.d.ts
+++ b/cli/js/lib.deno.ns.d.ts
@@ -1663,6 +1663,7 @@ declare namespace Deno {
     UnexpectedEof: ErrorConstructor;
     BadResource: ErrorConstructor;
     Http: ErrorConstructor;
+    Busy: ErrorConstructor;
   };
 
   /** **UNSTABLE**: potentially want names to overlap more with browser.
diff --git a/cli/js/tests/read_file_test.ts b/cli/js/tests/read_file_test.ts
index 1b709b1f4..0d3cdf422 100644
--- a/cli/js/tests/read_file_test.ts
+++ b/cli/js/tests/read_file_test.ts
@@ -57,3 +57,9 @@ unitTest({ perms: { read: false } }, async function readFilePerm(): Promise<
   }
   assert(caughtError);
 });
+
+unitTest({ perms: { read: true } }, function readFileSyncLoop(): void {
+  for (let i = 0; i < 256; i++) {
+    Deno.readFileSync("cli/tests/fixture.json");
+  }
+});