Added new error for cases when addStorageAndWait() is used with .allowSynchronousLightweightMigration but migrations are only allowed asynchronously (related to #277)

Sources/CSError.swift

@@ -218,6 +218,17 @@ extension CoreStoreError: CoreStoreSwiftType, _ObjectiveCBridgeableError {
             }
             self = .progressiveMigrationRequired(localStoreURL: localStoreURL)
 
+        case .asynchronousMigrationRequired:
+            guard
+                let localStoreURL = info["localStoreURL"] as? URL,
+                case let nsError as NSError = info["NSError"]
+                else {
+
+                    self = .unknown
+                    return
+            }
+            self = .asynchronousMigrationRequired(localStoreURL: localStoreURL, NSError: nsError)
+            
         case .internalError:
             guard case let nsError as NSError = info["NSError"] else {
                 

Sources/CoreStore+CustomDebugStringConvertible.swift

@@ -138,6 +138,10 @@ extension CoreStoreError: CustomDebugStringConvertible, CoreStoreDebugStringConv
             firstLine = ".progressiveMigrationRequired"
             info.append(("localStoreURL", localStoreURL))
 
+        case .asynchronousMigrationRequired(let localStoreURL):
+            firstLine = ".asynchronousMigrationRequired"
+            info.append(("localStoreURL", localStoreURL))
+            
         case .internalError(let NSError):
             firstLine = ".internalError"
             info.append(("NSError", NSError))

Sources/CoreStoreError.swift

@@ -54,6 +54,11 @@ public enum CoreStoreError: Error, CustomNSError, Hashable {
      */
     case progressiveMigrationRequired(localStoreURL: URL)
 
+    /**
+     The `LocalStorage` was configured with `.allowSynchronousLightweightMigration`, but the model can only be migrated asynchronously.
+     */
+    case asynchronousMigrationRequired(localStoreURL: URL, NSError: NSError)
+    
     /**
      An internal SDK call failed with the specified `NSError`.
      */
@@ -93,6 +98,9 @@ public enum CoreStoreError: Error, CustomNSError, Hashable {
         case .progressiveMigrationRequired:
             return CoreStoreErrorCode.progressiveMigrationRequired.rawValue
 
+        case .asynchronousMigrationRequired:
+            return CoreStoreErrorCode.asynchronousMigrationRequired.rawValue
+            
         case .internalError:
             return CoreStoreErrorCode.internalError.rawValue
             
@@ -128,6 +136,12 @@ public enum CoreStoreError: Error, CustomNSError, Hashable {
                 "localStoreURL": localStoreURL
             ]
 
+        case .asynchronousMigrationRequired(let localStoreURL, let nsError):
+            return [
+                "localStoreURL": localStoreURL,
+                "NSError": nsError
+            ]
+            
         case .internalError(let nsError):
             return [
                 "NSError": nsError
@@ -162,6 +176,10 @@ public enum CoreStoreError: Error, CustomNSError, Hashable {
         case (.progressiveMigrationRequired(let url1), .progressiveMigrationRequired(let url2)):
             return url1 == url2
 
+        case (.asynchronousMigrationRequired(let url1, let NSError1), .asynchronousMigrationRequired(let url2, let NSError2)):
+            return url1 == url2
+                && NSError1.isEqual(NSError2)
+            
         case (.internalError(let NSError1), .internalError(let NSError2)):
             return NSError1.isEqual(NSError2)
             
@@ -205,6 +223,10 @@ public enum CoreStoreError: Error, CustomNSError, Hashable {
         case .progressiveMigrationRequired(let localStoreURL):
             hasher.combine(localStoreURL)
 
+        case .asynchronousMigrationRequired(let localStoreURL, let nsError):
+            hasher.combine(localStoreURL)
+            hasher.combine(nsError)
+
         case .internalError(let nsError):
             hasher.combine(nsError)
 
@@ -262,6 +284,11 @@ public enum CoreStoreErrorCode: Int {
      */
     case progressiveMigrationRequired
 
+    /**
+     The `LocalStorage` was configured with `.allowSynchronousLightweightMigration`, but the model can only be migrated asynchronously.
+     */
+    case asynchronousMigrationRequired
+    
     /**
      An internal SDK call failed with the specified "NSError" userInfo key.
      */

Sources/DataStack.swift

@@ -345,6 +345,18 @@ public final class DataStack: Equatable {
                     )
                     return storage
                 }
+                catch let error as NSError where storage.localStorageOptions.contains(.allowSynchronousLightweightMigration) && error.isCoreDataMigrationError {
+
+                    let storeError = CoreStoreError.asynchronousMigrationRequired(
+                        localStoreURL: fileURL,
+                        NSError: error
+                    )
+                    CoreStore.log(
+                        storeError,
+                        "Failed to add \(cs_typeName(storage)) to the stack."
+                    )
+                    throw storeError
+                }
             }
             catch {