fix: guard against IndexError when repr() returns empty string in formatPair() - #240

Bug

formatPair() accesses value[0] unconditionally to check whether the stringified value looks like a Python string literal. When an object's __repr__ returns an empty string '', this raises IndexError: string index out of range whenever output is formatted across multiple lines (triggered by a long prefix, a long line, or a multiline value).

Reproduction

from icecream import ic

class EmptyRepr:
    def __repr__(self):
        return ''

ic.configureOutput(prefix='x' * 100)  # force multiline path
ic(EmptyRepr())  # IndexError: string index out of range

Fix

Add a len(value) >= 2 guard before the character-index access so that empty (and single-character) strings skip the string-literal check instead of crashing.

# Before
looksLikeAString = (value[0] + value[-1]) in ["''", '""']

# After
looksLikeAString = len(value) >= 2 and (value[0] + value[-1]) in ["''", '""']