fix bug in utils.leInt2Buff #28

[nooma-42]

What type of PR is this?

Bug Fix

What does this PR do? Why is it needed?

issue #28 pointed out What type of PR is this?

Bug Fix

What does this PR do? Why is it needed?

issue #28 pointed out leInt2Buff return depend on len, and make an explanation on why this could be potentially harmful to user not familiar with library. This bug is fixed by rearrange the function arguments.

issue #28 showed the output from the first piece of code, the truncated results of its script is now normal without any trailing 1.

num:  42n
leInt2Buff len = undefined:  Uint8Array(1) [ 42 ]
leInt2Buff len = 1:  Uint8Array(1) [ 42 ]
leInt2Buff len = 2:  Uint8Array(2) [ 42, 0 ]
leInt2Buff len = 3:  Uint8Array(3) [ 42, 0, 0 ]
leInt2Buff len = 4:  Uint8Array(4) [ 42, 0, 0, 0 ]
leInt2Buff len = 5:  Uint8Array(5) [ 42, 0, 0, 0, 0 ]
leInt2Buff len = 6:  Uint8Array(6) [ 42, 0, 0, 0, 0, 0 ]
leInt2Buff len = 7:  Uint8Array(7) [
  42, 0, 0, 0,
   0, 0, 0
]
leInt2Buff len = 8:  Uint8Array(8) [
  42, 0, 0, 0,
   0, 0, 0, 0
]

Which issues(s) does this PR fix?

bug in utils.leInt2Buff #28

Other notes for review

[phated]

@nooma-42 This looks great! Can you add some tests for it?

[nooma-42]

@nooma-42 This looks great! Can you add some tests for it?

I've added tests for leInt2Buff and BeInt2Buff, testing with the case introduced in original issue (28)
I also corrected a typo in src/util.js

Before I made the commit, the code below will never run, since it's same condition as previous clause.

else if (i + 4 <= buff.length) {