fixup! Resolve owner's key correctly in case of property-ref

Missing space in exception message

Author: fredericDelaporte

src/NHibernate/Async/Type/CollectionType.cs

@@ -357,7 +357,7 @@ public async Task<object> GetKeyOfOwnerAsync(object owner, ISessionImplementor s
 			// This should not happen. If that changes, at least yield null, instead of yielding
 			// a value of an unexpected type.
 			throw new AssertionFailure(
-				$"Unable to correctly resolve the owner key, property {foreignKeyPropertyName} for" +
+				$"Unable to correctly resolve the owner key, property {foreignKeyPropertyName} for " +
 				$"collection {role}. Unresolved value '{key}', key type '{keyType}', owner '{owner}'.");
 		}
 	}

src/NHibernate/Type/CollectionType.cs

@@ -535,7 +535,7 @@ public object GetKeyOfOwner(object owner, ISessionImplementor session)
 			// This should not happen. If that changes, at least yield null, instead of yielding
 			// a value of an unexpected type.
 			throw new AssertionFailure(
-				$"Unable to correctly resolve the owner key, property {foreignKeyPropertyName} for" +
+				$"Unable to correctly resolve the owner key, property {foreignKeyPropertyName} for " +
 				$"collection {role}. Unresolved value '{key}', key type '{keyType}', owner '{owner}'.");
 		}