import: safely handle unsupported files

Fixes #1191

app/task/project/import/import.h

@@ -42,6 +42,16 @@ public:
     return command_;
   }
 
+  const QStringList& GetInvalidFiles() const
+  {
+    return invalid_files_;
+  }
+
+  bool HasInvalidFiles() const
+  {
+    return !invalid_files_.isEmpty();
+  }
+
 protected:
   virtual bool Run() override;
 
@@ -58,6 +68,8 @@ private:
 
   int file_count_;
 
+  QStringList invalid_files_;
+
 };
 
 OLIVE_NAMESPACE_EXIT