# variable() errors informatively

    lower and upper must be numeric
    lower has class: numeric
    lower has length: 1
    upper has class: logical
    upper has length: 1

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    lower and upper must be numeric
    lower has class: numeric
    lower has length: 1
    upper has class: function
    upper has length: 1

---

    lower and upper must be numeric
    lower has class: logical
    lower has length: 1
    upper has class: numeric
    upper has length: 1

---

    lower and upper must be numeric
    lower has class: function
    lower has length: 1
    upper has class: numeric
    upper has length: 1

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    incompatible dimensions: 3x1, 2x1

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    upper bounds must be greater than lower bounds
    lower is: 1
    upper is: 1

# constrained variable constructors error informatively

    cholesky variables must be square
    However its dimension is: "2x3"

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    `dim` can either be a scalar or a vector of length 2
    However `dim` has length 3, and contains: "2, 2, 2"

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    the final dimension of a simplex variable must have more than one element

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    the final dimension of a simplex variable must have more than one element

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    the final dimension of an ordered variable must have more than one element

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    the final dimension of an ordered variable must have more than one element