Expanding empty strings is valid but pointless;
macro args already skipped doing so, now other
`beginExpansion` calls do too.
This also fixes failed interpolations (which were
already non-fatal) to continue reading characters,
not evaluate to their initial '{' character.
Widths and fractional widths greater than 255 would overflow a
uint8_t and wrap around to smaller values.
Total formatted lengths greater than the avilable buffer size
would overflow it and potentially corrupt memory.
Fixes#830Closes#831
Widths and fractional widths greater than 255 would overflow a
uint8_t and wrap around to smaller values.
Total formatted lengths greater than the avilable buffer size
would overflow it and potentially corrupt memory.
Fixes#830Closes#831
