Newlines at the end of interpolations?

[nicuveo]

Currently, even in the middle of multiline strings, newlines cannot be added at the end of an interpolation.

// rejected
a:"""
\(
3+1
)
"""

// allowed
a:"""
\(
3+1 )
"""

Is there a reason why, or is it just a limitation of the lexer? Would it be incorrect for an implementation to allow those extra newlines?