chore(types): provide type for source maps (#5670)

Author: wjhsf

packages/@lwc/compiler/src/transformers/shared.ts

@@ -4,14 +4,15 @@
  * SPDX-License-Identifier: MIT
  * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
  */
+import type { BabelFileResult } from '@babel/core';
 import type { CompilerDiagnostic } from '@lwc/errors';
 
 /** The object returned after transforming code. */
 export interface TransformResult {
     /** The compiled source code. */
     code: string;
     /** The generated source map. */
-    map: unknown;
+    map: BabelFileResult['map'];
     /** Any diagnostic warnings that may have occurred. */
     warnings?: CompilerDiagnostic[];
     /**

packages/@lwc/compiler/src/transformers/style.ts

@@ -7,6 +7,7 @@
 import * as styleCompiler from '@lwc/style-compiler';
 import { normalizeToCompilerError, TransformerErrors, CompilerAggregateError } from '@lwc/errors';
 
+import type { BabelFileResult } from '@babel/core';
 import type { NormalizedTransformOptions } from '../options';
 import type { TransformResult } from './shared';
 
@@ -63,6 +64,6 @@ export default function styleTransform(
     // the styles doesn't make sense, the transform returns an empty mappings.
     return {
         code: res.code,
-        map: { mappings: '' },
+        map: { mappings: '' } as BabelFileResult['map'],
     };
 }

packages/@lwc/compiler/src/transformers/template.ts

@@ -13,6 +13,7 @@ import {
 } from '@lwc/errors';
 import { compile } from '@lwc/template-compiler';
 
+import type { BabelFileResult } from '@babel/core';
 import type { NormalizedTransformOptions } from '../options';
 import type { TransformResult } from './shared';
 
@@ -93,7 +94,7 @@ export default function templateTransform(
     // the template doesn't make sense, the transform returns an empty mappings.
     return {
         code: result.code,
-        map: { mappings: '' },
+        map: { mappings: '' } as BabelFileResult['map'],
         warnings,
         cssScopeTokens: result.cssScopeTokens,
     };

packages/@lwc/ssr-compiler/src/index.ts

@@ -12,7 +12,7 @@ import type { ComponentTransformOptions, TemplateTransformOptions } from './shar
 
 export interface CompilationResult {
     code: string;
-    map: unknown;
+    map: undefined;
 }
 
 export function compileComponentForSSR(