allow loading from absolute path, validate env var

src/bootstrap.js

@@ -5,6 +5,7 @@ const require = createRequire(import.meta.url);
 
 import { cosmiconfig } from "cosmiconfig";
 import decamelize from "decamelize";
+import fs from "fs";
 import path from "path";
 import yargs from "yargs";
 import { hideBin } from "yargs/helpers";
@@ -17,13 +18,22 @@ import logger from "./logger.js";
 import { loadAllPlugins, resolveUserPlugins } from "./plugins.js";
 
 async function getCosmiConfig(cosmiconfigOptions) {
+  let configFile;
+
   if (process.env.V8R_CONFIG_FILE) {
-    cosmiconfigOptions.searchPlaces = [process.env.V8R_CONFIG_FILE];
+    if (!fs.existsSync(process.env.V8R_CONFIG_FILE)) {
+      throw new Error(`File ${process.env.V8R_CONFIG_FILE} does not exist.`);
+    }
+    configFile = await cosmiconfig("v8r", cosmiconfigOptions).load(
+      process.env.V8R_CONFIG_FILE,
+    );
+  } else {
+    cosmiconfigOptions.stopDir = process.cwd();
+    configFile = (await cosmiconfig("v8r", cosmiconfigOptions).search(
+      process.cwd(),
+    )) || { config: {} };
   }
-  cosmiconfigOptions.stopDir = process.cwd();
-  const configFile = (await cosmiconfig("v8r", cosmiconfigOptions).search(
-    process.cwd(),
-  )) || { config: {} };
+
   if (configFile.filepath) {
     logger.info(`Loaded config file from ${getRelativeFilePath(configFile)}`);
     logger.info(