fix(env): handle fstat errors gracefully when loading .env files

On WSL1, fstat() on certain files (including empty .env files) can fail
unexpectedly. Previously, these errors would propagate up via `try` and
cause the entire script to fail silently with exit code 1.

This change catches fstat() errors in both loadEnvFile() and
loadEnvFileDynamic() and handles them gracefully by:
1. Printing a warning (unless quiet mode is enabled)
2. Marking the .env file as "loaded" (empty) to prevent retries
3. Continuing execution normally

Reproduction steps on WSL1:
1. Create test.js with content: console.log('test');
2. Run: bun test.js (works fine, outputs "test")
3. Create empty .env: touch .env
4. Run: bun test.js (previously: no output, exit 1; now: outputs "test")

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/env_loader.zig

@@ -751,7 +751,14 @@ pub const Loader = struct {
                 break :brk pos;
             }
 
-            const stat = try file.stat();
+            const stat = file.stat() catch |err| {
+                // On WSL1, fstat() can fail on certain files. Handle gracefully.
+                if (!this.quiet) {
+                    Output.prettyErrorln("<r><yellow>warn<r>: {s} when loading {s} file", .{ @errorName(err), base });
+                }
+                @field(this, base) = logger.Source.initPathString(base, "");
+                return;
+            };
 
             if (stat.size == 0 or stat.kind != .file) {
                 @field(this, base) = logger.Source.initPathString(base, "");
@@ -824,7 +831,14 @@ pub const Loader = struct {
                 break :brk pos;
             }
 
-            const stat = try file.stat();
+            const stat = file.stat() catch |err| {
+                // On WSL1, fstat() can fail on certain files. Handle gracefully.
+                if (!this.quiet) {
+                    Output.prettyErrorln("<r><yellow>warn<r>: {s} when loading {s} file", .{ @errorName(err), file_path });
+                }
+                try this.custom_files_loaded.put(file_path, logger.Source.initPathString(file_path, ""));
+                return;
+            };
 
             if (stat.size == 0 or stat.kind != .file) {
                 try this.custom_files_loaded.put(file_path, logger.Source.initPathString(file_path, ""));

test/cli/run/env.test.ts

@@ -820,6 +820,36 @@ test("NODE_ENV=test loads .env.test even when .env.production exists", () => {
   expect(stdout).toBe("test");
 });
 
+test("empty .env file does not cause errors", () => {
+  // Regression test: On WSL1, an empty .env file could cause fstat() to fail,
+  // which would propagate as an unhandled error and cause the script to fail silently.
+  const dir = tempDirWithFiles("dotenv-empty", {
+    ".env": "", // Empty .env file
+    "index.ts": "console.log('success');",
+  });
+  const { stdout } = bunRun(`${dir}/index.ts`);
+  expect(stdout).toBe("success");
+});
+
+test("empty .env.local file does not cause errors", () => {
+  const dir = tempDirWithFiles("dotenv-empty-local", {
+    ".env.local": "", // Empty .env.local file
+    "index.ts": "console.log('success');",
+  });
+  const { stdout } = bunRun(`${dir}/index.ts`);
+  expect(stdout).toBe("success");
+});
+
+test("empty .env alongside non-empty .env.local works", () => {
+  const dir = tempDirWithFiles("dotenv-empty-mixed", {
+    ".env": "", // Empty
+    ".env.local": "FOO=bar", // Non-empty
+    "index.ts": "console.log(process.env.FOO);",
+  });
+  const { stdout } = bunRun(`${dir}/index.ts`);
+  expect(stdout).toBe("bar");
+});
+
 describe("env loader buffer handling", () => {
   test("handles large quoted values with escape sequences", () => {
     // This test ensures the env loader properly handles large values that exceed the initial buffer size