Address comments

Signed-off-by: Xuanwo <github@xuanwo.io>

src/sccache.ts

@@ -1,3 +1,17 @@
+// Copyright 2023 Mozilla Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 import * as core from '@actions/core';
 import {
   downloadTool,
@@ -58,7 +72,7 @@ function getArch(): Error | string {
     case 'arm64':
       return 'aarch64';
     default:
-      return Error('not supported arch');
+      return Error('Unsupported arch "${process.arch}"');
   }
 }
 
@@ -71,7 +85,7 @@ function getPlatform(): Error | string {
     case 'linux':
       return 'unknown-linux-musl';
     default:
-      return Error('not supported platform');
+      return Error('Unsupported platform "${process.platform}"');
   }
 }