vscode: migrate to more type-safe assert impl

editors/code/src/installation/download_artifact.ts

@@ -1,10 +1,10 @@
 import * as vscode from "vscode";
 import * as path from "path";
 import { promises as fs } from "fs";
-import { strict as assert } from "assert";
 
 import { ArtifactReleaseInfo } from "./interfaces";
 import { downloadFile } from "./download_file";
+import { assert } from "../util";
 
 /**
  * Downloads artifact from given `downloadUrl`.
@@ -19,11 +19,10 @@ export async function downloadArtifact(
     installationDir: string,
     displayName: string,
 ) {
-    await fs.mkdir(installationDir).catch(err => assert.strictEqual(
-        err?.code,
-        "EEXIST",
+    await fs.mkdir(installationDir).catch(err => assert(
+        err?.code === "EEXIST",
         `Couldn't create directory "${installationDir}" to download ` +
-        `${artifactFileName} artifact: ${err.message}`
+        `${artifactFileName} artifact: ${err?.message}`
     ));
 
     const installationPath = path.join(installationDir, artifactFileName);

editors/code/src/installation/download_file.ts

@@ -2,8 +2,7 @@ import fetch from "node-fetch";
 import * as fs from "fs";
 import * as stream from "stream";
 import * as util from "util";
-import { strict as assert } from "assert";
-import { log } from "../util";
+import { log, assert } from "../util";
 
 const pipeline = util.promisify(stream.pipeline);
 

editors/code/src/installation/server.ts

@@ -1,13 +1,12 @@
 import * as vscode from "vscode";
 import * as path from "path";
-import { strict as assert } from "assert";
 import { promises as dns } from "dns";
 import { spawnSync } from "child_process";
 
 import { BinarySource } from "./interfaces";
 import { fetchArtifactReleaseInfo } from "./fetch_artifact_release_info";
 import { downloadArtifact } from "./download_artifact";
-import { log } from "../util";
+import { log, assert } from "../util";
 
 export async function ensureServerBinary(source: null | BinarySource): Promise<null | string> {
     if (!source) {

editors/code/src/util.ts

@@ -1,22 +1,31 @@
 import * as lc from "vscode-languageclient";
 import * as vscode from "vscode";
+import { strict as nativeAssert } from "assert";
 
-let enabled: boolean = false;
+export function assert(condition: boolean, explanation: string): asserts condition {
+    try {
+        nativeAssert(condition, explanation);
+    } catch (err) {
+        log.error(`Assertion failed:`, explanation);
+        throw err;
+    }
+}
 
 export const log = {
+    enabled: true,
     debug(message?: any, ...optionalParams: any[]): void {
-        if (!enabled) return;
+        if (!log.enabled) return;
         // eslint-disable-next-line no-console
         console.log(message, ...optionalParams);
     },
     error(message?: any, ...optionalParams: any[]): void {
-        if (!enabled) return;
+        if (!log.enabled) return;
         debugger;
         // eslint-disable-next-line no-console
         console.error(message, ...optionalParams);
     },
     setEnabled(yes: boolean): void {
-        enabled = yes;
+        log.enabled = yes;
     }
 };