bIErrorCheck: bIErrorCheck
In SharonLutz/bayesIndirect: Runs the bayesIndirect Function

Performs error checks on the input for the bayesIndirect function.

1	bIErrorCheck(x, k, y, Z = NULL, nCov = 0, plot0 = FALSE, nIts = 50000, nBurn = 10000, propGamma1Pi = 0.7, cx = 10, pix = 0.5)

`x`	is the exposure, such as the SNP.
`k`	is the mediator.
`y`	is the normally distributed outcome.
`Z`	is the matrix of covariates.
`nCov`	is the number of covariates. nCov = 0, 1 or 2.
`plot0`	true if density plot should be outputted or false otherwise.
`nIts`	is the number of iterations of the MCMC.
`nBurn`	is the Burn-in period.
`propGamma1Pi`	is the probability of gamma from the Bernoulli distribution.
`cx`	is the variance of beta X from the normal distribution.
`pix`	is the probability that beta x is sampled from the normal distribution.