Teach the lint script about DERIVED_FILE_DIR

A `sourceTree` the script does not know makes the whole project file
undecodable, failing the `[Lint] Check AppLocalizedString usage` phase after the
Swift compile has already succeeded.
Failing there is right — an unresolvable reference means a file silently goes
unlinted — but the report was
`The data couldn't be read because it isn't in the correct format`, naming
neither the setting nor the value.

`localizedDescription` was throwing that detail away.
Interpolating the error itself yields
`Cannot initialize SourceTree from invalid String value SOME_FUTURE_DIR`,
with the offending object's UUID and key path.

---

Generated with the help of Claude Code, https://claude.com/claude-code

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: mokagio

Scripts/BuildPhases/LintAppLocalizedStringsUsage.swift

@@ -78,7 +78,7 @@ extension Xcodeproj {
             return object.path.map { groupURL.appendingPathComponent($0) } ?? groupURL
         case .projectRoot:
             return object.path.map { URL(fileURLWithPath: $0, relativeTo: projectDirectory) } ?? projectDirectory
-        case .buildProductsDir, .devDir, .sdkDir:
+        case .buildProductsDir, .derivedFileDir, .devDir, .sdkDir:
             print("\(self.projectURL.path): warning: Reference \(objectUUID) is relative to \(object.sourceTree.rawValue), which is not supported by the linter")
             return nil
         }
@@ -206,6 +206,7 @@ extension Xcodeproj {
         case group = "<group>"
         case projectRoot = "SOURCE_ROOT"
         case buildProductsDir = "BUILT_PRODUCTS_DIR"
+        case derivedFileDir = "DERIVED_FILE_DIR"
         case devDir = "DEVELOPER_DIR"
         case sdkDir = "SDKROOT"
         var description: String { rawValue }
@@ -321,7 +322,7 @@ do {
     print("Done! \(violationsFound) violation(s) found.")
     exit(violationsFound > 0 ? 1 : 0)
 } catch let error {
-    print("\(projectPath): error: Error while parsing the project file \(projectPath): \(error.localizedDescription)")
+    print("\(projectPath): error: Error while parsing the project file \(projectPath): \(error)")
     exit(2)
 }