handle unknown knowledge base errors

src/knowledge_base.cpp

@@ -51,13 +51,16 @@ void obelisk::KnowledgeBase::createTable(std::function<const char*()> function)
     if (result != SQLITE_OK)
     {
         logSqliteError(result);
-        throw obelisk::KnowledgeBaseException("something happened");
-    }
         if (tmp)
         {
             std::string errmsg(tmp);
             throw obelisk::KnowledgeBaseException(errmsg);
         }
+        else
+        {
+            throw obelisk::KnowledgeBaseException();
+        }
+    }
 }
 
 // TODO: log files?

src/knowledge_base.h

@@ -43,6 +43,11 @@ namespace obelisk
             const std::string errorMessage_;
 
         public:
+            KnowledgeBaseException() :
+                errorMessage_("an unknown error occured")
+            {
+            }
+
             KnowledgeBaseException(const std::string& errorMessage) :
                 errorMessage_(errorMessage)
             {