Make ObjectiveCError type Sendable without warnings (#73)

* Make ObjectiveCError type Sendable without warnings

* Add comments to offsetInFile checking

Author: dfed

Sources/CacheAdvance/CacheReader.swift

@@ -54,11 +54,13 @@ final class CacheReader {
                 if offsetInFile == endOffset {
                     break
                 } else if offsetInFile > endOffset {
+                    // The messages on disk are out of sync with our header data.
                     throw CacheAdvanceError.fileCorrupted
                 }
             }
         }
         if let endOffset = endOffset, offsetInFile != endOffset {
+            // If we finished reading messages but our offset in the file is less (or greater) than our expected ending offset, our header data is incorrect.
             throw CacheAdvanceError.fileCorrupted
         }
         return encodedMessages

Sources/CacheAdvance/ObjectiveC.swift

@@ -34,7 +34,9 @@ final class ObjectiveC {
         SwiftTryCatch.try({
             result = .success(work())
         }, catch: { exception in
-            result = .failure(ObjectiveCError(exception: exception))
+            result = .failure(ObjectiveCError(
+                exceptionName: exception.name,
+                reason: exception.reason))
         })
 
         switch result {
@@ -51,5 +53,6 @@ struct ObjectiveCTryFailure: Error {}
 
 /// A `throw`able NSException.
 struct ObjectiveCError: Error {
-    let exception: NSException
+    let exceptionName: NSExceptionName
+    let reason: String?
 }