Fix potential crash when reloading the config after removing a branch log command

When cycling to the last branch log command, and then editing the config to
remove one or more log commands, lazygit would crash with an out of bounds panic
when returning to it. Fix this by resetting the log index to 0 when it is out of
bounds. (I think resetting to 0 is better than clamping, although it doesn't
matter much.)

pkg/commands/git_commands/branch.go

@@ -278,6 +278,10 @@ func (self *BranchCommands) allBranchesLogCandidates() []string {
 func (self *BranchCommands) AllBranchesLogCmdObj() *oscommands.CmdObj {
 	candidates := self.allBranchesLogCandidates()
 
+	if self.allBranchesLogCmdIndex >= len(candidates) {
+		self.allBranchesLogCmdIndex = 0
+	}
+
 	i := self.allBranchesLogCmdIndex
 	return self.cmd.New(str.ToArgv(candidates[i])).DontLog()
 }