Heap size issues ?

[Ierlandfan]

I want to rule out heap size issues in my sketch so I want to use a const char instead of String
Altrunner version has that but added the virtual function "error" I don't understand.
(I am trying to implement that version into PlaneSpotter ofcourse) to make it more robust.
Can you come up with an example to explain the virtual void error(); example?
(I cannot seem to find a way to reach Altrunner so that's why I ask)