A plugin specifier could not be resolved or imported.

Previously this was an unhandled throw out of a Promise.all, so a typo'd plugin name surfaced as a raw ERR_MODULE_NOT_FOUND stack with no indication that a plugin was at fault or which entry named it.

import * as Config from './config.ts';

const failure = Config.PluginLoadFailed({ specifier: 'esbuild-plugin-vue' }, { cause: new Error('ERR_MODULE_NOT_FOUND') });
failure.data.specifier; // 'esbuild-plugin-vue' — the entry at fault, resolver error under `.cause`