Proper package checks in make_style.sh (#335)

make_style.sh

@@ -1,21 +1,8 @@
 #!/bin/bash
-if ! [ -x "$(command -v npx sass)" ]; then
-  echo 'Error: sass is not installed.' >&2
-  exit 1
-fi
-
-if ! [ -x "$(command -v npx postcss)" ]; then
-  echo 'Error: postcss is not installed.' >&2
-  exit 1
-fi
-
-if ! [ -x "$(command -v npx autoprefixer)" ]; then
-  echo 'Error: autoprefixer is not installed.' >&2
-  exit 1
-fi
-
 cd "$(dirname "$0")" || exit
 
+node scripts/check-package-installed.js postcss sass autoprefixer || exit
+
 build_style() {
   echo "Creating $1 style..."
   cp resources/vars-$1.scss resources/vars.scss

scripts/check-package-installed.js

@@ -0,0 +1,28 @@
+// @ts-check
+import { createRequire } from "node:module";
+
+const require = createRequire(import.meta.url);
+
+if (process.argv.length < 3) {
+  throw new Error("Please specify a package/packages to check.");
+}
+
+/**
+ * @type {string[]}
+ */
+const failedPackages = [];
+
+for (let i = 2; i < process.argv.length; ++i) {
+  const packageName = process.argv[i];
+  try {
+    require(packageName);
+  } catch {
+    failedPackages.push(packageName);
+  }
+}
+
+if (failedPackages.length !== 0) {
+  throw new Error(
+    `${failedPackages.join(", ")} ${failedPackages.length === 1 ? "is" : "are"} not installed.`,
+  );
+}