fix(jsii): TypeError: Cannot read property 'getJsDocTags' of undefined

When a trailing semicolon was left after a method body, the compiler
would choke with a `TypeError` due to attempting to read the JSDoc tags
of an `undefined` symbol.

This checks for this particular case and ignores the "class member" that
is represented by the dangling semicolon; and emits a diagnostic message
informing users the token could be removed.

Fixes #2098

packages/jsii/lib/assembler.ts

@@ -1240,10 +1240,18 @@ export class Assembler implements Emitter {
       }
 
       for (const memberDecl of classDecl.members) {
-        // The "??" is to get to the __constructor symbol (getSymbolAtLocation wouldn't work there..)
-        const member =
-          this._typeChecker.getSymbolAtLocation(memberDecl.name!) ??
-          ((memberDecl as any).symbol as ts.Symbol);
+        if (ts.isSemicolonClassElement(memberDecl)) {
+          this._diagnostics.push(
+            JsiiDiagnostic.JSII_9996_UNNECESSARY_TOKEN.create(memberDecl),
+          );
+          continue;
+        }
+
+        const member: ts.Symbol = ts.isConstructorDeclaration(memberDecl)
+          ? (memberDecl as any).symbol
+          : this._typeChecker.getSymbolAtLocation(
+              ts.getNameOfDeclaration(memberDecl)!,
+            )!;
 
         if (
           !(declaringType.symbol.getDeclarations() ?? []).find(

packages/jsii/lib/compiler.ts

@@ -7,6 +7,7 @@ import * as ts from 'typescript';
 
 import { Assembler } from './assembler';
 import { Emitter } from './emitter';
+import { JsiiDiagnostic } from './jsii-diagnostic';
 import { ProjectInfo } from './project-info';
 import * as utils from './utils';
 
@@ -246,7 +247,9 @@ export class Compiler implements Emitter {
 
       diagnostics.push(...assmEmit.diagnostics);
     } catch (e) {
-      LOG.error(`Error during type model analysis: ${e}\n${e.stack}`);
+      diagnostics.push(
+        JsiiDiagnostic.JSII_9997_UNKNOWN_ERROR.createDetached(e),
+      );
       hasErrors = true;
     }
 

packages/jsii/lib/helpers.ts

@@ -77,7 +77,7 @@ export async function compileJsiiForTest(
       console.error(error.messageText);
       // logDiagnostic() doesn't work out of the box, so console.error() it is.
     }
-    if (errors.length > 0) {
+    if (errors.length > 0 || emitResult.emitSkipped) {
       throw new Error('There were compiler errors');
     }
     const assembly = await fs.readJSON('.jsii', { encoding: 'utf-8' });

packages/jsii/lib/jsii-diagnostic.ts

@@ -708,7 +708,7 @@ export class JsiiDiagnostic implements ts.Diagnostic {
   public static readonly JSII_9002_UNRESOLVEABLE_TYPE = Code.error({
     code: 9002,
     formatter: (reference: string) =>
-      `Unable to resolve type "${reference}". It may be @iternal or not exported from the module's entry point (as configured in "package.json" as "main").`,
+      `Unable to resolve type "${reference}". It may be @internal or not exported from the module's entry point (as configured in "package.json" as "main").`,
     name: 'miscellaneous/unresolveable-type',
   });
 
@@ -726,6 +726,19 @@ export class JsiiDiagnostic implements ts.Diagnostic {
     name: 'miscellaneous/unable-to-compute-signature',
   });
 
+  public static readonly JSII_9996_UNNECESSARY_TOKEN = Code.message({
+    code: 9996,
+    formatter: () => 'Unnecessary token, consider removing it',
+    name: 'miscellaneous/unnecessary-token',
+  });
+
+  public static readonly JSII_9997_UNKNOWN_ERROR = Code.error({
+    code: 9997,
+    formatter: (error: Error) =>
+      `Unknown error: ${error.message} -- ${error.stack}`,
+    name: 'miscellaneous/unknown-error',
+  });
+
   public static readonly JSII_9998_UNSUPORTED_NODE = Code.message({
     code: 9998,
     formatter: (kindOrMessage: ts.SyntaxKind | string) =>

packages/jsii/test/quirks.test.ts

@@ -0,0 +1,32 @@
+import { sourceToAssemblyHelper } from '../lib';
+
+// ----------------------------------------------------------------------
+test('trailing semicolon after method is correctly ignored', async () => {
+  const assembly = await sourceToAssemblyHelper(`
+    export class Foo {
+      private readonly initialized: boolean;
+
+      public constructor() {
+        this.initialized = true;
+      };
+
+      public method() { return this.initialized; };
+    }
+  `);
+
+  expect(assembly.types!['testpkg.Foo']).toEqual({
+    assembly: 'testpkg',
+    fqn: 'testpkg.Foo',
+    kind: 'class',
+    methods: [
+      {
+        locationInModule: { filename: 'index.ts', line: 9 },
+        name: 'method',
+        returns: { type: { primitive: 'boolean' } },
+      },
+    ],
+    initializer: { locationInModule: { filename: 'index.ts', line: 5 } },
+    locationInModule: { filename: 'index.ts', line: 2 },
+    name: 'Foo',
+  });
+});