Fix lsp missing crash (#594)

* Fix crashes where workspaceFolders was undefined

* Fix fallback to built-in lsp when bsdk cannot be resolved

* Better error message wording

src/LanguageServerManager.spec.ts

@@ -18,6 +18,7 @@ import {
 import { util } from './util';
 import { GlobalStateManager } from './GlobalStateManager';
 import { LocalPackageManager } from './managers/LocalPackageManager';
+import { expectThrowsAsync } from './testHelpers.spec';
 const Module = require('module');
 const sinon = createSandbox();
 
@@ -345,6 +346,27 @@ describe('LanguageServerManager', () => {
         //these tests take a long time (due to running `npm install`)
         this.timeout(5 * 60 * 1000);
 
+        it('returns info when absolute dir already exists', async () => {
+            const versionInfo = s`${tempDir}/node_modules/brighterscript`;
+            fsExtra.outputJsonSync(s`${tempDir}/node_modules/brighterscript/package.json`, {
+                version: '0.65.0'
+            });
+            expect(
+                await languageServerManager['ensureBscVersionInstalled'](versionInfo)
+            ).to.eql({
+                packageDir: s`${tempDir}/node_modules/brighterscript`,
+                versionInfo: versionInfo,
+                version: '0.65.0'
+            });
+        });
+
+        it('throws when dir does not exist', async () => {
+            const versionInfo = s`${tempDir}/node_modules/brighterscript`;
+            await expectThrowsAsync(async () => {
+                await languageServerManager['ensureBscVersionInstalled'](versionInfo);
+            }, `"${s(versionInfo)}" does not contain a package.json file`);
+        });
+
         it('installs a bsc version when not present', async () => {
             const info = await languageServerManager['ensureBscVersionInstalled']('0.65.0');
             expect(info).to.eql({

src/LanguageServerManager.ts

@@ -423,8 +423,8 @@ export class LanguageServerManager {
             this.selectedBscInfo = await this.ensureBscVersionInstalled(versionInfo);
         } catch (e) {
             console.error(e);
-            //fall back to the embedded version, and show a popup
-            await vscode.window.showErrorMessage(`Can't find language server for "${versionInfo}". Did you forget to run \`npm install\`? Using embedded version v${this.embeddedBscInfo.version} instead.`);
+            //fall back to the embedded version, and show a popup (don't await the popup because that blocks this flow)
+            void vscode.window.showErrorMessage(`Language server failure. Did you forget \`npm install\`? Using embedded version ${this.embeddedBscInfo.version}. Can't find language server for "${versionInfo}"`);
             this.selectedBscInfo = this.embeddedBscInfo;
         }
 
@@ -439,7 +439,7 @@ export class LanguageServerManager {
         if (versionInfo === 'embedded') {
             return {
                 type: 'dir',
-                value: this.embeddedBscInfo.packageDir
+                value: s`${this.embeddedBscInfo.packageDir}`
             };
         } else {
             return this.localPackageManager.parseVersionInfo(versionInfo, cwd);
@@ -513,8 +513,12 @@ export class LanguageServerManager {
 
         //if this is a directory, use it as-is
         if (parsed.type === 'dir') {
+            //if the directory does not exist, throw an error
+            if (await fsExtra.pathExists(s`${parsed.value}/package.json`) === false) {
+                throw new Error(`"${parsed.value}" does not contain a package.json file`);
+            }
             return {
-                packageDir: parsed.value,
+                packageDir: s`${parsed.value}`,
                 version: fsExtra.readJsonSync(s`${parsed.value}/package.json`, { throws: false })?.version ?? parsed.value,
                 versionInfo: versionInfo
             };

src/testHelpers.spec.ts

@@ -0,0 +1,32 @@
+import { expect } from 'chai';
+
+export function expectThrows(callback: () => any, expectedMessage: string | undefined = undefined, failedTestMessage = 'Expected to throw but did not') {
+    let wasExceptionThrown = false;
+    try {
+        callback();
+    } catch (e) {
+        wasExceptionThrown = true;
+        if (expectedMessage) {
+            expect(e.message).to.eql(expectedMessage);
+        }
+    }
+    if (wasExceptionThrown === false) {
+        throw new Error(failedTestMessage);
+    }
+}
+
+
+export async function expectThrowsAsync(callback: () => any, expectedMessage: string | undefined = undefined, failedTestMessage = 'Expected to throw but did not') {
+    let wasExceptionThrown = false;
+    try {
+        await Promise.resolve(callback());
+    } catch (e) {
+        wasExceptionThrown = true;
+        if (expectedMessage) {
+            expect(e.message).to.eql(expectedMessage);
+        }
+    }
+    if (wasExceptionThrown === false) {
+        throw new Error(failedTestMessage);
+    }
+}