Use safe resource bundle lookup for Prism (#21)

Author: gonzalezreal

Sources/Textual/Internal/Helpers/Bundle.swift

@@ -0,0 +1,47 @@
+import Foundation
+
+private class Token {}
+
+extension Bundle {
+  // NB: Alternative to `Bundle.module` that does not crash when the bundle is not found
+  static let textual: Bundle? = {
+    let bundleName = "textual_Textual"
+
+    let overrides: [URL]
+    #if DEBUG
+      // The 'PACKAGE_RESOURCE_BUNDLE_PATH' name is preferred since the expected value is a path. The
+      // check for 'PACKAGE_RESOURCE_BUNDLE_URL' will be removed when all clients have switched over.
+      // This removal is tracked by rdar://107766372.
+      if let override = ProcessInfo.processInfo.environment["PACKAGE_RESOURCE_BUNDLE_PATH"]
+        ?? ProcessInfo.processInfo.environment["PACKAGE_RESOURCE_BUNDLE_URL"]
+      {
+        overrides = [URL(fileURLWithPath: override)]
+      } else {
+        overrides = []
+      }
+    #else
+      overrides = []
+    #endif
+
+    let candidates =
+      overrides + [
+        // Bundle should be present here when the package is linked into an App.
+        Bundle.main.resourceURL,
+
+        // Bundle should be present here when the package is linked into a framework.
+        Bundle(for: Token.self).resourceURL,
+
+        // For command-line tools.
+        Bundle.main.bundleURL,
+      ]
+
+    for candidate in candidates {
+      let bundlePath = candidate?.appendingPathComponent(bundleName + ".bundle")
+      if let bundle = bundlePath.flatMap(Bundle.init(url:)) {
+        return bundle
+      }
+    }
+
+    return nil
+  }()
+}

Sources/Textual/Internal/Highlighter/CodeTokenizer.swift

@@ -33,7 +33,7 @@ struct CodeToken: Hashable, Sendable {
       }
 
       guard
-        let bundleURL = Bundle.module.url(
+        let bundleURL = Bundle.textual?.url(
           forResource: "prism-bundle",
           withExtension: "js"
         ),