Terminal.cpp:9 error: 'class String' has no member named 'isEmpty'

[MartinBzm]

OS: Linux, Board: Arduino Nano, IDE: Arduino IDE 2.3.7
When compiling it shows the error: Terminal.cpp:9 error: 'class String' has no member named 'isEmpty' .

Terminal.cpp
01 #include "MjolnFS.h"
02
03 void MjolnFileSystem::processCommand(String command)
04 {
05    if (command.startsWith("mk "))
06    {
07        String filename, data;
08        extractArgs(command, filename, data);
09        if (!filename.isEmpty() && !data.isEmpty())
10        {

Is there a pre-requisite I did not read about ?
Cheers!

[styropyr0]

Hello @MartinBzm ,
Thanks for raising this issue.
​The reason is because the Arduino Nano (which uses an AVR chip) uses a very lean version of the Arduino core that simply doesn't have that specific function defined. But there is a workaround, instead of isEmpty(), please use length comparison, .length() > 0.

I'll fix this within the library in the future, along with some new features for security and defragmentation.

Have a nice day