Running examples in 'sjPlot-Ex.R' failed
The error most likely occurred in:

> ### Name: sjp.poly
> ### Title: Plot polynomials for (generalized) linear regression
> ### Aliases: sjp.poly
> 
> ### ** Examples
> 
> library(sjmisc)
> data(efc)
> # linear fit. loess-smoothed line indicates a more
> # or less cubic curve
> sjp.poly(efc$c160age, efc$quol_5, 1)
Polynomial degrees: 1
---------------------
p(x^1): 0.000

`geom_smooth()` using formula 'y ~ x'
> 
> # quadratic fit
> sjp.poly(efc$c160age, efc$quol_5, 2)
Polynomial degrees: 2
---------------------
p(x^1): 0.078
p(x^2): 0.533

`geom_smooth()` using formula 'y ~ x'
> 
> # linear to cubic fit
> sjp.poly(efc$c160age, efc$quol_5, 1:4, show.scatter = FALSE)
Polynomial degrees: 1
---------------------
p(x^1): 0.000

Polynomial degrees: 2
---------------------
p(x^1): 0.078
p(x^2): 0.533

Polynomial degrees: 3
---------------------
p(x^1): 0.012
p(x^2): 0.001
p(x^3): 0.000

Polynomial degrees: 4
---------------------
p(x^1): 0.777
p(x^2): 0.913
p(x^3): 0.505
p(x^4): 0.254

`geom_smooth()` using formula 'y ~ x'
> 
> 
> # fit sample model
> fit <- lm(tot_sc_e ~ c12hour + e17age + e42dep, data = efc)
> # inspect relationship between predictors and response
> plot_model(fit, type = "slope")
`geom_smooth()` using formula 'y ~ x'
`geom_smooth()` using formula 'y ~ x'
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,  :
  pseudoinverse used at 4.015
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,  :
  neighborhood radius 2.015
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,  :
  reciprocal condition number  2.8666e-15
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,  :
  There are other near singularities as well. 1
> # "e17age" does not seem to be linear correlated to response
> # try to find appropiate polynomial. Grey line (loess smoothed)
> # indicates best fit. Looks like x^4 has the best fit,
> # however, only x^3 has significant p-values.
> sjp.poly(fit, "e17age", 2:4, show.scatter = FALSE)
Error in FUN(X, Y, ...) : non-numeric argument to binary operator
Calls: sjp.poly ... model.frame.default -> eval -> eval -> <Anonymous> -> outer
Execution halted