Unexpected behavior of limits

[JorgeLLH]

The version I use: AngouriMath.FSharp 1.3.0<!--
Unexpected behaviour or bug: <!--
The following limit:
let a_limit = Core.parser("limit(1/(ln(x+(x*x+1)^0.5))-(1/ln(x+1)), x, 0)";;
(a_limit.Evaled).EvalNumerical() |> double;;

Results in:
val it : double = nan

Actual answer should be -1/2

Another limit (related to the Gamma function, upper limit of the integral)
let upper_lim_Gamma=Core.parsed("limit((x^(5-1))*(e)^(-x), x, +oo)");;
(upper_lim_Gamma.Evaled).EvalNumerical() |> double;;

Results in:
val it : double = nan

Actual value should be 0.

Smaller values 20 instead of infinity for example result in correct values.

Another limit (answer is 1/e) giving an error:
let limit_b = Core.parsed("limit(((x!)/x^x)^(1/x), x, +oo)");;
(limit_b.Evaled).EvalNumerical() |> double;;
AngouriMath.Core.Exceptions.CannotEvalException: Result cannot be represented as a simple number! Use EvaluableNumerical to check beforehand.
at AngouriMath.Entity.EvalNumerical()
at <StartupCode$FSI_0027>.$FSI_0027.main@()
Stopped due to error

Smaller values produce the expected behavior:
let limit_b = Core.parsed("limit(((x!)/x^x)^(1/x), x, 4)");;
(limit_b.Evaled).EvalNumerical() |> double;;
val it : double = 0.5533409599

Thanks for your time!
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