fix: crash when removing account while messages are being returned

pkg/pmapi/addresses.go

@@ -18,6 +18,7 @@
 package pmapi
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 
@@ -116,7 +117,7 @@ func (l AddressList) Main() *Address {
 			return addr
 		}
 	}
-	return l[0] // Should not happen.
+	return nil
 }
 
 // ByEmail gets an address by email. Returns nil if no address is found.
@@ -218,10 +219,14 @@ func (c *client) UnlockAddresses(passphrase []byte) (err error) {
 	return
 }
 
-func (c *client) KeyRingForAddressID(addrID string) *pmcrypto.KeyRing {
-	addr := c.addresses.ByID(addrID)
-	if addr == nil {
-		addr = c.addresses.Main()
+func (c *client) KeyRingForAddressID(addrID string) (*pmcrypto.KeyRing, error) {
+	if addr := c.addresses.ByID(addrID); addr != nil {
+		return addr.KeyRing(), nil
 	}
-	return addr.KeyRing()
+
+	if addr := c.addresses.Main(); addr != nil {
+		return addr.KeyRing(), nil
+	}
+
+	return nil, errors.New("no such address ID")
 }

pkg/pmapi/client.go

@@ -157,7 +157,7 @@ type Client interface {
 	CreateAttachment(att *Attachment, r io.Reader, sig io.Reader) (created *Attachment, err error)
 	DeleteAttachment(attID string) (err error)
 
-	KeyRingForAddressID(string) (kr *pmcrypto.KeyRing)
+	KeyRingForAddressID(string) (kr *pmcrypto.KeyRing, err error)
 	GetPublicKeysForEmail(string) ([]PublicKey, bool, error)
 }
 

pkg/pmapi/mocks/mocks.go

@@ -433,11 +433,12 @@ func (mr *MockClientMockRecorder) IsConnected() *gomock.Call {
 }
 
 // KeyRingForAddressID mocks base method
-func (m *MockClient) KeyRingForAddressID(arg0 string) *crypto.KeyRing {
+func (m *MockClient) KeyRingForAddressID(arg0 string) (*crypto.KeyRing, error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "KeyRingForAddressID", arg0)
 	ret0, _ := ret[0].(*crypto.KeyRing)
-	return ret0
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
 }
 
 // KeyRingForAddressID indicates an expected call of KeyRingForAddressID