Provide more context when failing to search for mapping models #299

Sources/InferredSchemaMappingProvider.swift

@@ -31,6 +31,7 @@ import Foundation
 
 /**
  A `SchemaMappingProvider` that tries to infer model migration between two `DynamicSchema` versions by searching all `xcmappingmodel`s from `Bundle.allBundles` or by relying on lightweight migration if possible. Throws an error if lightweight migration is impossible for the two `DynamicSchema`. This mapping is automatically used as a fallback mapping provider, even if no mapping providers are explicitly declared in the `StorageInterface`.
+ - Note: For security reasons, `InferredSchemaMappingProvider` will not search `Bundle.allFrameworks` by default. If the `xcmappingmodel`s are bundled within a framework, use `XcodeSchemaMappingProvider` instead and provide `Bundle(for: <a class in the framework>` to its initializer.
  */
 public final class InferredSchemaMappingProvider: Hashable, SchemaMappingProvider {
     
@@ -53,7 +54,7 @@ public final class InferredSchemaMappingProvider: Hashable, SchemaMappingProvide
     // MARK: SchemaMappingProvider
     
     public func cs_createMappingModel(from sourceSchema: DynamicSchema, to destinationSchema: DynamicSchema, storage: LocalStorage) throws -> (mappingModel: NSMappingModel, migrationType: MigrationType) {
-        
+
         let sourceModel = sourceSchema.rawModel()
         let destinationModel = destinationSchema.rawModel()
         
@@ -85,8 +86,13 @@ public final class InferredSchemaMappingProvider: Hashable, SchemaMappingProvide
             )
         }
         catch {
-            
-            throw CoreStoreError(error)
+
+            let coreStoreError = CoreStoreError(error)
+            CoreStore.log(
+                coreStoreError,
+                "\(cs_typeName(self)) failed to find migration mappings from version model \"\(sourceSchema.modelVersion)\" to \"\(destinationSchema.modelVersion)\" in the \(cs_typeName(storage)) at URL \"\(storage.fileURL)\". The local storage may be corrupt or the \(cs_typeName(storage)) initializer may be missing the correct \(cs_typeName(SchemaMappingProvider.self))"
+            )
+            throw coreStoreError
         }
     }
 }