../..//apps/er-coap/er-coap-observe.c:237:15: warning: unused variable
‘content’ [-Wunused-variable]
This was caused by a buffer that was declared, but used only in
commented out code.
The variable was moved to the commented out block.
The block was surrounded by an #if 0 ... #endif to make it easier to
uncomment.
Everything still compiles with the code in question uncommented.