UcoinErrors handling

src/sakia/core/account.py

src/sakia/core/community.py

src/sakia/core/net/api/bma/access.py

src/sakia/core/net/node.py

src/sakia/core/registry/identities.py

src/sakia/core/registry/identity.py

src/sakia/core/txhistory.py

src/sakia/gui/certification.py

src/sakia/gui/community_tile.py

src/sakia/gui/community_view.py

src/sakia/gui/identities_tab.py

src/sakia/gui/process_cfg_community.py

src/sakia/gui/transactions_tab.py

src/sakia/gui/widgets/search_user.py

...ts/functional/process_cfg_community/test_add_community.py

src/sakia/tests/mocks/bma/init_new_community.py

src/sakia/tests/mocks/bma/new_blockchain.py

src/sakia/tests/mocks/bma/nice_blockchain.py

src/sakia/tests/unit/core/test_network.py