fix: build source maps (#2416)

chompfile.toml

@@ -5,7 +5,7 @@ default-task = 'build'
 extensions = [
   'chomp@0.1:npm',
   'chomp@0.1:footprint',
-  'chomp@0.1:terser',
+  './terser.js',
   'chomp@0.1:rollup',
   'chomp@0.1:ncc'
 ]

terser.js

@@ -0,0 +1,40 @@
+Chomp.addExtension('chomp@0.1:npm');
+
+Chomp.registerTemplate('terser', function (task) {
+  if (task.engine || task.run)
+    throw new Error('"engine", "run" not configurable for Terser template.');
+
+  const opts = task.templateOptions;
+  const preamble = opts.output?.preamble;
+  const pjsonVersion = typeof preamble === 'string' && preamble.includes('#PJSON_VERSION');
+  const { autoInstall } = opts;
+  const targetName = task.targets[0].split('/').pop();
+  if (opts.sourceMap === true)
+    opts.sourceMap = { filename: targetName, url: '$TARGET', includeSources: true };
+  const optionsStr = JSON.stringify(opts, null, 2).replace(/\n/g, '\n  ').replace('"$TARGET"', 'basename(process.env.TARGET)');
+
+  return [{
+    name: task.name,
+    targets: task.targets,
+    deps: [...task.deps, ...pjsonVersion ? ['package.json'] : [], ...ENV.CHOMP_EJECT ? ['npm:install'] : ['node_modules/terser']],
+    engine: 'node',
+    run: `  import { readFileSync, writeFileSync } from 'fs';
+  import { basename } from 'path';
+  import { minify } from 'terser';
+
+${pjsonVersion ? `  const pjson = JSON.parse(readFileSync('package.json', 'utf8'));` : ''}
+  const { code, map } = await minify({ [basename(process.env.DEP)]: readFileSync(process.env.DEP, 'utf8') }, ${
+    pjsonVersion ? optionsStr.replace('"preamble": ' + JSON.stringify(preamble), '"preamble": `' + preamble.replace(/(\`|\${)/, '\\$1').replace('#PJSON_VERSION', '${pjson.version}') + '`') : optionsStr
+  });
+
+  writeFileSync(process.env.TARGET, code);
+${opts.sourceMap ? '  writeFileSync(\`\${process.env.TARGET}.map\`, map);\n' : ''}`
+  }, ...ENV.CHOMP_EJECT ? [] : [{
+    template: 'npm',
+    templateOptions: {
+      autoInstall,
+      packages: ['terser@5'],
+      dev: true
+    }
+  }]];
+});