Refine matrix element type message

[selkamand]

Motivation

• Improve clarity of non-numeric matrix/array error messages by extracting and using the element type when formatting the message in the numeric check.

Description

• Update is_numeric_with_matrix_message in R/is_functions.R to store element_type <- typeof(x) and use it when constructing the matrix/array error string.

Testing

• Ran devtools::document() which completed successfully; ran devtools::test() and all tests passed (1006 tests passed); ran devtools::check() which completed but reported 1 WARNING (qpdf not available) and 1 NOTE (unable to verify current time), causing R CMD check to return with warnings.

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Codex Task

[selkamand]

switching from class to typeof could be an interesting alternative approach. Not without its own quirks (e.g. returns 'integer' / 'double') instead of 'numeric'.

I think this current solution is fine though.