Error compiling on ESP-12E

[bwjm19]

I am facing a problem when i compile the coapserver.ino. These are the errors. Appreciate if anyone can guide me the direction

C:\Users\user\Documents\Arduino\libraries\ESP-CoAP-master\coap_server.cpp: In member function 'bool coapServer::loop()':
C:\Users\user\Documents\Arduino\libraries\ESP-CoAP-master\coap_server.cpp:186:11: error: no match for 'operator+=' (operand types are 'String' and 'char [(((int)request->coapPacket::options[i].coapOption::length) + 1)]')
186 | url += urlname;
| ~~~~^~~~~~~~~~
In file included from C:\Users\user\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/Arduino.h:286,
from C:\Users\user\Documents\Arduino\libraries\ESP-CoAP-master\coap_server.h:14,
from C:\Users\user\Documents\Arduino\libraries\ESP-CoAP-master\coap_server.cpp:11:
C:\Users\user\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/WString.h:133:17: note: candidate: 'template String& String::operator+=(const T&)'
133 | String &operator +=(const T &rhs) {
| ^~~~~~~~
C:\Users\user\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/WString.h:133:17: note: template argument deduction/substitution failed:
C:\Users\user\Documents\Arduino\libraries\ESP-CoAP-master\coap_server.cpp:186:14: note: variable-sized array type 'char [(((int)request->coapPacket::options[i].coapOption::length) + 1)]' is not a valid template argument
186 | url += urlname;
| ^~~~~~~
exit status 1
Error compiling for board NodeMCU 1.0 (ESP-12E Module).

[Cecchellone]

Same here

[Ochoalog]

Same here too!