Fix webpack source maps

webpack.config.ts

@@ -1,10 +1,11 @@
-import { resolve } from "path";
+import { writeFile } from "fs/promises";
+import { dirname, isAbsolute, relative, resolve } from "path";
 import { fileURLToPath } from "url";
 import exports, { Configuration } from "webpack";
 
-const { WatchIgnorePlugin } = exports;
+const { WatchIgnorePlugin, SourceMapDevToolPlugin } = exports;
 
-let dirname = fileURLToPath(new URL(".", import.meta.url));
+let dirName = fileURLToPath(new URL(".", import.meta.url));
 
 let generator = (env: any, argv: any): Configuration[] =>
 {
@@ -23,8 +24,30 @@ let generator = (env: any, argv: any): Configuration[] =>
             },
             output: {
                 filename: "[name].js",
-                path: resolve(dirname, "lib"),
-                devtoolFallbackModuleFilenameTemplate: "../[resource-path]",
+                path: resolve(dirName, "lib"),
+                devtoolModuleFilenameTemplate: (context: any) =>
+                {
+                    let path = context.absoluteResourcePath;
+
+                    // For regular files, this statement is true.
+                    if (isAbsolute(path))
+                    {
+                        return path;
+                    }
+                    else
+                    {
+                        let fallback = new SourceMapDevToolPlugin().moduleFilenameTemplate;
+
+                        if (typeof fallback === "function")
+                        {
+                            return fallback(context);
+                        }
+                        else
+                        {
+                            return fallback;
+                        }
+                    }
+                },
                 libraryTarget: "module",
                 chunkFormat: "module",
                 environment: {
@@ -58,7 +81,48 @@ let generator = (env: any, argv: any): Configuration[] =>
                         paths: [
                             /\.d\.ts$/
                         ]
-                    })
+                    }),
+                {
+                    apply(compiler)
+                    {
+                        compiler.hooks.assetEmitted.tap(
+                            {
+                                name: "AdjustSourceMap"
+                            },
+                            async (file, { content, source, outputPath, compilation, targetPath }) =>
+                            {
+                                if (file.endsWith(".map"))
+                                {
+                                    try
+                                    {
+                                        let sourceMap = JSON.parse(content.toString());
+
+                                        if (Array.isArray(sourceMap.sources))
+                                        {
+                                            sourceMap.sources = sourceMap.sources.map(
+                                                (source: string) =>
+                                                {
+                                                    // Prevent `webpack://` sources from being changed
+                                                    if (isAbsolute(source))
+                                                    {
+                                                        // Change regular file paths to relative ones
+                                                        return relative(dirname(targetPath), source);
+                                                    }
+                                                    else
+                                                    {
+                                                        return source;
+                                                    }
+                                                });
+
+                                            // Overwrite old source map
+                                            await writeFile(targetPath, JSON.stringify(sourceMap));
+                                        }
+                                    }
+                                    catch {}
+                                }
+                            });
+                    }
+                }
             ],
             module: {
                 rules: [
@@ -69,10 +133,10 @@ let generator = (env: any, argv: any): Configuration[] =>
                             {
                                 loader: "ts-loader",
                                 options: {
-                                    configFile: resolve(dirname, "tsconfig.build.json"),
+                                    configFile: resolve(dirName, "tsconfig.build.json"),
                                     projectReferences: true,
                                     compilerOptions: {
-                                        outDir: resolve(dirname, "lib", "temp")
+                                        outDir: resolve(dirName, "lib", "temp")
                                     }
                                 }
                             }