Correctly exit Stdlib tests on failure (#1888)

Signed-off-by: Takeshi Yoneda <t.y.mathetake@gmail.com>

internal/integration_test/stdlibs/bench_test.go

@@ -68,7 +68,7 @@ var (
 		readTestCase: func(fpath string, fname string) (_ []byte, c wazero.ModuleConfig, stdout, stderr *os.File, err error) {
 			bin, err := os.ReadFile(fpath)
 			c, stdout, stderr = defaultModuleConfig()
-			c.WithFSConfig(wazero.NewFSConfig().WithDirMount(".", "/")).
+			c = c.WithFSConfig(wazero.NewFSConfig().WithDirMount(".", "/")).
 				WithArgs("test.wasm")
 			return bin, c, stdout, stderr, err
 		},
@@ -87,7 +87,7 @@ var (
 				WithDirMount(os.TempDir(), "/tmp")
 
 			c, stdout, stderr = defaultModuleConfig()
-			c.WithFSConfig(fsconfig).
+			c = c.WithFSConfig(fsconfig).
 				WithArgs(fname, "-test.v")
 
 			return bin, c, stdout, stderr, err
@@ -113,7 +113,7 @@ var (
 			normalizedTestdir := normalizeOsPath(testdir)
 
 			c, stdout, stderr = defaultModuleConfig()
-			c.WithFSConfig(
+			c = c.WithFSConfig(
 				wazero.NewFSConfig().
 					WithDirMount(sysroot, "/").
 					WithDirMount(os.TempDir(), "/tmp")).
@@ -223,11 +223,13 @@ func requireZeroExitCode(b *testing.B, err error, stdout, stderr *os.File) {
 	b.Helper()
 	if se, ok := err.(*sys.ExitError); ok {
 		if se.ExitCode() != 0 { // Don't err on success.
-			stdoutBytes, err := io.ReadAll(stdout)
-			require.NoError(b, err)
-			stderrBytes, err := io.ReadAll(stderr)
-			require.NoError(b, err)
+			stdoutBytes, _ := io.ReadAll(stdout)
+			stderrBytes, _ := io.ReadAll(stderr)
 			require.NoError(b, err, "stdout: %s\nstderr: %s", string(stdoutBytes), string(stderrBytes))
 		}
+	} else if err != nil {
+		stdoutBytes, _ := io.ReadAll(stdout)
+		stderrBytes, _ := io.ReadAll(stderr)
+		require.NoError(b, err, "stdout: %s\nstderr: %s", string(stdoutBytes), string(stderrBytes))
 	}
 }