Tiny, minor error that doesn't really affect anybody. The NBT parser uses the following regex (Double specifically but applies to most of the other regex used):

[-+]?[0-9]*\\.?[0-9]+[d|D]

The | (pipebar) is used as a literal value check rather than as an OR operator, so the following creates a Double when it should be a String instead:

tagname:1|

The other datatypes use the pipebar as a value, including IntArrays (resulting in a String due to non-parseable Integer rather than an expected List with the record tossed).

\\[[-+\\d|,\\s]+\\]

tagname:[1,2,|,4]

The fix is to simply remove the pipebar:

[-+]?[0-9]*\\.?[0-9]+[dD]
\\[[-+\\d,\\s]+\\]