Cellular: failure when deleting created context is not considered as an error

If delete fails there is nothing we or application can do. There is no point
returning an error for this. This affects to AT_CellularContext::disconnect
not returning an error if context delete fails.

Author: Teppo Järvelin

UNITTESTS/stubs/AT_CellularContext_stub.cpp

@@ -172,9 +172,8 @@ pdp_type_t AT_CellularContext::string_to_pdp_type(const char *pdp_type)
 }
 
 // PDP Context handling
-nsapi_error_t AT_CellularContext::delete_current_context()
+void AT_CellularContext::delete_current_context()
 {
-    return NSAPI_ERROR_OK;
 }
 
 nsapi_error_t AT_CellularContext::do_user_authentication()

features/cellular/framework/AT/AT_CellularContext.cpp

@@ -309,7 +309,7 @@ pdp_type_t AT_CellularContext::string_to_pdp_type(const char *pdp_type_str)
 }
 
 // PDP Context handling
-nsapi_error_t AT_CellularContext::delete_current_context()
+void AT_CellularContext::delete_current_context()
 {
     tr_info("Delete context %d", _cid);
     _at.clear_error();
@@ -321,7 +321,8 @@ nsapi_error_t AT_CellularContext::delete_current_context()
         _new_context_set = false;
     }
 
-    return _at.get_last_error();
+    // there is nothing we can do if deleting of context fails. No point reporting an error (for example disconnect).
+    _at.clear_error();
 }
 
 nsapi_error_t AT_CellularContext::do_user_authentication()

features/cellular/framework/AT/AT_CellularContext.h

@@ -115,7 +115,7 @@ class AT_CellularContext : public CellularContext, public AT_CellularBase {
     nsapi_error_t find_and_activate_context();
     nsapi_error_t activate_ip_context();
     void check_and_deactivate_context();
-    nsapi_error_t delete_current_context();
+    void delete_current_context();
     nsapi_error_t check_operation(nsapi_error_t err, ContextOperation op);
     void ciot_opt_cb(mbed::CellularNetwork::CIoT_Supported_Opt ciot_opt);
     virtual void do_connect_with_retry();