fix: Remove try-catch from Buffer.readFrom, readFromSync (#6161)

cli/js/buffer.ts

@@ -158,38 +158,30 @@ export class Buffer implements Reader, ReaderSync, Writer, WriterSync {
   async readFrom(r: Reader): Promise<number> {
     let n = 0;
     while (true) {
-      try {
-        const i = this.#grow(MIN_READ);
-        this.#reslice(i);
-        const fub = new Uint8Array(this.#buf.buffer, i);
-        const nread = await r.read(fub);
-        if (nread === null) {
-          return n;
-        }
-        this.#reslice(i + nread);
-        n += nread;
-      } catch (e) {
+      const i = this.#grow(MIN_READ);
+      this.#reslice(i);
+      const fub = new Uint8Array(this.#buf.buffer, i);
+      const nread = await r.read(fub);
+      if (nread === null) {
         return n;
       }
+      this.#reslice(i + nread);
+      n += nread;
     }
   }
 
   readFromSync(r: ReaderSync): number {
     let n = 0;
     while (true) {
-      try {
-        const i = this.#grow(MIN_READ);
-        this.#reslice(i);
-        const fub = new Uint8Array(this.#buf.buffer, i);
-        const nread = r.readSync(fub);
-        if (nread === null) {
-          return n;
-        }
-        this.#reslice(i + nread);
-        n += nread;
-      } catch (e) {
+      const i = this.#grow(MIN_READ);
+      this.#reslice(i);
+      const fub = new Uint8Array(this.#buf.buffer, i);
+      const nread = r.readSync(fub);
+      if (nread === null) {
         return n;
       }
+      this.#reslice(i + nread);
+      n += nread;
     }
   }
 }

cli/tests/unit/buffer_test.ts

@@ -7,6 +7,8 @@ import {
   assertEquals,
   assert,
   assertStringContains,
+  assertThrows,
+  assertThrowsAsync,
   unitTest,
 } from "./test_util.ts";
 
@@ -202,6 +204,9 @@ unitTest(async function bufferReadFrom(): Promise<void> {
     const fub = new Uint8Array(testString.length);
     await empty(b, s, fub);
   }
+  assertThrowsAsync(async function () {
+    await new Buffer().readFrom(null!);
+  });
 });
 
 unitTest(async function bufferReadFromSync(): Promise<void> {
@@ -221,6 +226,9 @@ unitTest(async function bufferReadFromSync(): Promise<void> {
     const fub = new Uint8Array(testString.length);
     await empty(b, s, fub);
   }
+  assertThrows(function () {
+    new Buffer().readFromSync(null!);
+  });
 });
 
 unitTest(async function bufferTestGrow(): Promise<void> {

cli/tests/unit/test_util.ts

@@ -4,6 +4,7 @@ import { assert, assertEquals } from "../../../std/testing/asserts.ts";
 export {
   assert,
   assertThrows,
+  assertThrowsAsync,
   assertEquals,
   assertMatch,
   assertNotEquals,