Root finder for the fourth power polynomial

restart;

e1:= 0.5; e2:=0.2;theta:=5;yeq:=e2;

f:=(theta*x-1)*(1-x)*(1+beta*x^2)-y;
g:=x/(1+beta*x^2); gs:=unapply(g,x);

fs:=subs(y=yeq,f);

assumptions:=x>1/theta, x<1,beta>0,beta<1,gs(x)>e1;
solve(fs=0,x,useassumptions) assuming assumptions;

Warning, solve may not respect assumed property 'real' on 'x/(beta*x^2+1)'.

Error, (in type/realcons) too many levels of recursion

gs2:=subs(beta=0.6,gs(x));

sol:= solve(subs(beta=0.6,fs=0),x,useassumptions) assuming x>1/theta, x<1;

subs(x=sol[1],gs2);