You shouldn't be changing the loop variable i in a for loop.
Normally, the loop variable is incremented at the end of the loop. No idea what you have in Expression1 and Expression2 but if you want to to know the index when an error occurs, you can just access it normally in the catch. The following code gives the resulting output:
for i = 1:10
fprintf('Current i = %d\n', i);
try
if(i == 5)
error('error')
end
catch ME
fprintf('Error at i = %d\n', i);
end
end
Current i = 1
Current i = 2
Current i = 3
Current i = 4
Current i = 5
Error at i = 5
Current i = 6
Current i = 7
Current i = 8
Current i = 9
Current i = 10
