[BUG REPORT] Print error message: A case where the the check_if will always overflow

[Math-O5]

Describe the bug
When user type incomplete programs, the "check_if(tokens[i + 1])" in sim/simc_parse.py will always overflow, if there is not tokens[i + 1].

The program typed by the use is clearly wrong, but the program should treat this properly.

To Reproduce
Complie this simc code:

test.simc:

MAIN
    if()

MAIN
    var

MAIN
    f

MAIN
    array overflow

Ouput error:

...
  File "/home/math-o5/anaconda3/lib/python3.7/site-packages/simc/simc_parser.py", line 673, in check_ptr
    if tokens[i].type == "multiply":
IndexError: list index out of range

Expected behavior
A kind message error for user

Desktop (please complete the following information):

• OS: Fedora 30, Ubuntu 18

[frankhart2018]

Yeah currently it just expects something to be there, there should be an index out of range check too in check_if.

[frankhart2018]

Passing the index as argument and processing check_if only if the index is in range will fix this.

[jigyasudhingra]

I would like to work on this @frankhart2018.

[Math-O5]

@jigyasudhingra All yours. :)