How can I use WhenEvent to stop the integration? [duplicate]

Question

I have a questions about stopping the integration. I calculate the function as the following. It gives the message: "At NN=58.7035438......, the step size is effectively zero; singularity or stiff system suspected.". I want to stop the numerical integration when the step size is effectively zero. I know there is a function called WhenEvent. But, there are no items specifying the step size. Any ideas for solving this? (If there are ideas other than using WhenEvent, it is also welcomed. ) The code is the following. Thank you very much for your sincere help.

(* Define the numerical solving *)
numsol[M_, TRinitial_, Tiinitial_, TRinitialrate_, Tiinitialrate_, \[Alpha]_, ABS\[Mu]_, \[Iota]1_, KK_, Nini_, Nend_] :=NDSolve[{(*Equation of motion of TR[NN]*)
(ParametrizedVVReal[M, \[Alpha], 
     Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
     ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
     TR[NN], Ti[
      NN],(*CC*) (ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
          M))*(((\[Alpha]^2 - 7 \[Alpha] + 
             4) M)/(-\[Alpha] (\[Alpha] - 
             3) \[Iota]1))^(\[Alpha] - 1)]) TR''[
    NN] - (ParametrizedVVReal[M, \[Alpha], 
     Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
     ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
     TR[NN], Ti[
      NN],(*CC*)(ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
          M))*(((\[Alpha]^2 - 7 \[Alpha] + 
             4) M)/(-\[Alpha] (\[Alpha] - 
             3) \[Iota]1))^(\[Alpha] - 1)]) (TR'[NN]/(2 M^2))*
   (SigmaPrimeSquare[M, \[Alpha], TR[NN], TR'[NN], 
     Ti'[NN]]) + (ParametrizedVVReal[M, \[Alpha], 
     Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
     ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
     TR[NN], Ti[
      NN], (*CC*)(ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
          M))*(((\[Alpha]^2 - 7 \[Alpha] + 
             4) M)/(-\[Alpha] (\[Alpha] - 
             3) \[Iota]1))^(\[Alpha] - 1)]) (Christ111[
       TR[NN]] TR'[NN] TR'[NN] +
     Christ112[TR[NN]] TR'[NN] Ti'[NN] +
     Christ121[TR[NN]] Ti'[NN] TR'[NN] +
     Christ122[TR[NN]] Ti'[NN] Ti'[NN]) + (3) (ParametrizedVVReal[
     M, \[Alpha], Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
     ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
     TR[NN], Ti[
      NN], (*CC*)(ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
          M))*(((\[Alpha]^2 - 7 \[Alpha] + 
             4) M)/(-\[Alpha] (\[Alpha] - 
             3) \[Iota]1))^(\[Alpha] - 1)]) TR'[
    NN] + (3 M^2 - 
     0.5 (SigmaPrimeSquare[M, \[Alpha], TR[NN], TR'[NN], 
        Ti'[NN]])) (InvMetric[M, \[Alpha], TR[NN]][[1, 1]]*
      DTRParametrizedVVReal[M, \[Alpha], 
       Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
       ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
       TR[NN], Ti[NN]] +
     InvMetric[M, \[Alpha], TR[NN]][[1, 2]]*
      DTiParametrizedVVReal[M, \[Alpha], 
       Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
       ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
       TR[NN], Ti[NN]]) == 0,
(*Equation of motion of Ti[
NN]*)
(ParametrizedVVReal[M, \[Alpha], 
     Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
     ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
     TR[NN], Ti[
      NN],(*CC*)(ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
          M))*(((\[Alpha]^2 - 7 \[Alpha] + 
             4) M)/(-\[Alpha] (\[Alpha] - 
             3) \[Iota]1))^(\[Alpha] - 1)]) Ti''[
    NN] - (ParametrizedVVReal[M, \[Alpha], 
     Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
     ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
     TR[NN], Ti[
      NN],(*CC*)(ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
          M))*(((\[Alpha]^2 - 7 \[Alpha] + 
             4) M)/(-\[Alpha] (\[Alpha] - 
             3) \[Iota]1))^(\[Alpha] - 1)]) (Ti'[NN]/(2 M^2))*
   (SigmaPrimeSquare[M, \[Alpha], TR[NN], TR'[NN], 
     Ti'[NN]]) + (ParametrizedVVReal[M, \[Alpha], 
     Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
     ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
     TR[NN], Ti[
      NN],(*CC*)(ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
          M))*(((\[Alpha]^2 - 7 \[Alpha] + 
             4) M)/(-\[Alpha] (\[Alpha] - 
             3) \[Iota]1))^(\[Alpha] - 1)]) (Christ211[
       TR[NN]] TR'[NN] TR'[NN] +
     Christ212[TR[NN]] TR'[NN] Ti'[NN] +
     Christ221[TR[NN]] Ti'[NN] TR'[NN] +
     Christ222[TR[NN]] Ti'[NN] Ti'[NN]) + (3) (ParametrizedVVReal[
     M, \[Alpha], Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
     ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
     TR[NN], Ti[
      NN],(*CC*)(ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
          M))*(((\[Alpha]^2 - 7 \[Alpha] + 
             4) M)/(-\[Alpha] (\[Alpha] - 
             3) \[Iota]1))^(\[Alpha] - 1)]) Ti'[
    NN] + (3 M^2 - 
     0.5 (SigmaPrimeSquare[M, \[Alpha], TR[NN], TR'[NN], 
        Ti'[NN]])) (InvMetric[M, \[Alpha], TR[NN]][[2, 1]]*

      DTRParametrizedVVReal[M, \[Alpha], 
       Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
       ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
       TR[NN], Ti[NN]] +
     InvMetric[M, \[Alpha], TR[NN]][[2, 2]]*
      DTiParametrizedVVReal[M, \[Alpha], 
       Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
       ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
       TR[NN], Ti[NN]]) == 0,
(*Equation of motion of TSS*)

TSS'[NN] == 
 BBeta[M, \[Alpha], Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2,
    ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
   TR[NN], Ti[NN], TR'[NN], 
   Ti'[NN],(*CC*)(ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
        M))*(((\[Alpha]^2 - 7 \[Alpha] + 
           4) M)/(-\[Alpha] (\[Alpha] - 3) \[Iota]1))^(\[Alpha] - 
       1)] TSS[NN],
(* Equation of motion of TRS *)

TRS'[NN] == 
 AAlpha[M, \[Alpha], 
   Sqrt[\[Iota]1^2 + (KK*\[Iota]1)^2]*ABS\[Mu]/2, 
   ABS\[Mu], \[Iota]1*ABS\[Mu]^2, (KK*\[Iota]1) ABS\[Mu]^2, 
   TR[NN], Ti[NN], TR'[NN], 
   Ti'[
    NN],(*CC*)(ABS\[Mu]^2)*(\[Iota]1/(\[Alpha]*
        M))*(((\[Alpha]^2 - 7 \[Alpha] + 
           4) M)/(-\[Alpha] (\[Alpha] - 3) \[Iota]1))^(\[Alpha] - 
       1)] TSS[NN],
(*Boundary condition*)
TR[Nini] == TRinitial, 
Ti[Nini] == Tiinitial, TR'[Nini] == TRinitialrate, 
Ti'[Nini] == Tiinitialrate, TSS[Nini] == 1, TRS[Nini] == 0},
{TR[NN], Ti[NN], TR'[NN], Ti'[NN], TSS[NN], TSS'[NN], TRS[NN],TRS'[NN]}, {NN, Nini, Nend}, AccuracyGoal -> 10, PrecisionGoal -> 10, Method -> {"StiffnessSwitching", Method -> {"Extrapolation", Automatic}}(*,WhenEvent[MaxSteps\[Rule] 1000,"StopIntegration"]*)];

(* a function of Plotting TR and Ti by using the above numsol *)

FieldValuesPlot[M_, TRinitial_, Tiinitial_, TRinitialrate_, 
Tiinitialrate_, \[Alpha]_, ABS\[Mu]_, \[Iota]1_, KK_, Nini_, Nend_, color_] := 
Plot[Evaluate[{TR[NN], Ti[NN]} /. 
 numsol[M, TRinitial, Tiinitial, TRinitialrate, 
  Tiinitialrate, \[Alpha], ABS\[Mu], \[Iota]1, KK, Nini, 
  Nend]], {NN, Nini, Nend}, PlotRange -> {{Nini, Nend}, {-5, 200}},
 AxesLabel -> {"N", 
 "\!\(\*SubscriptBox[\(T\), \(R,I\)]\)/\!\(\*SubscriptBox[\(M\), \\(pl\)]\)"}, BaseStyle -> {FontSize -> 30},
PlotLegends -> {"\!\(\*SubscriptBox[\(T\), \(R\)]\)[N]", 
 "\!\(\*SubscriptBox[\(T\), \(I\)]\)[N]"}, 
PlotStyle -> {{color, Thick}, {color, Dashed}}];

(* Final output using the field plot *)
FieldValuesPlot[1, 70, 85, 10^(-5), 10^(-5), 4, 3*10^(-4), 25, -5, 0, 60, Red]