failed to read VASP: no atoms or `Number of atom types mismatches the number of counts`

[e-kwsm]

mctc-lib cc30341ec6a6c319489c4b4b5f7f2178db7a142d compiled by GCC 10.2.1 on Debian bullseye.

Prepare the following POSCAR:

POSCAR
3.0
1.0  0.0  0.0
0.0  1.0  0.0
0.0  0.0  1.0
 S
 1
direct
0.0  0.0  0.0

mctc-convert converts the file successfully:

$ mctc-convert POSCAR -o xyz -
1
poscar
S            0.00000000000000        0.00000000000000        0.00000000000000

However, if the indentation of the ion species and numbers are removed, i.e. changed to

S
1

mctc reads nothing:

$ mctc-convert POSCAR -o xyz -
0
poscar

Also, Number of atom types mismatches the number of counts is issued if changed to:

Si
1

 S
1

S
 1

The error does not occur if the above patterns are indented.

If the number of the ions are increased to ten,

• good: S\n10, Si\n10, Si\n10, Si\n 10
• bad: S\n10, S\n 10

[e-kwsm]

If the number of elements are two, mctc reads POSCAR successfully independently of the length of symbols and indentation.

poscar
3.0
1.0  0.0  0.0
0.0  1.0  0.0
0.0  0.0  1.0
B N
1 1
direct
0.0  0.0  0.0
0.5  0.5  0.5