I have the following error for this mathematica code:
(*Define end-effector position and orientation*) 
pe={0.5,0.2,0.8};(*Replace with desired position*) 
quat={0.7071,0.7071,0,0};(*Replace with desired orientation quaternion*) 
(*Compute inverse kinematics*) 
solutions=InverseKinematics6DOF[pe,quat,params];
(*Display solutions*)solutions//MatrixForm
Dot::dotsh: Tensors {{0.556613,0.830772,0.,-0.175},{0.,0.,-1.,0.495},{-0.830772,0.556613,0.,0.},{0.,0.,0.,1.}} and {0.5,0.334997,0.799997,1,1} have incompatible shapes.
Thread::tdlen: Objects of unequal length in {{0.309818,0.690182,0.,0.030625},{0.,0.,1.,0.245025},{0.690182,0.309818,0.,0.},{0.,0.,0.,1.}}+{0.25,0.112223,0.639996,1,1} cannot be combined.
Thread::tdlen: Objects of unequal length in ArcTan[{-0.5,-0.334997,-0.799997,-1,-1},{{0.556613,0.830772,0.,-0.175},{0.,0.,-1.,0.495},{-0.830772,0.556613,0.,0.},{0.,0.,0.,1.}}] cannot be combined.
Thread::tdlen: Objects of unequal length in -0.4445+{{0.309818,0.690182,0.,0.030625},{0.,0.,1.,0.245025},{0.690182,0.309818,0.,0.},{0.,0.,0.,1.}}+{0.25,0.112223,0.639996,1,1} cannot be combined.
General::stop: Further output of Thread::tdlen will be suppressed during this calculation.

The Mathematica code is:

Clear[InverseKinematics6DOF]
InverseKinematics6DOF[pe_,quat_, params_]:=Module[{
(*Extract position components*) 
px,py,pz,
(*Extract quaternion components*) 
q0,q1,q2,q3,
(*Compute rotation matrix from quaternion*) 
R,
(*End-effector orientation vectors*) 
ne,se,ae,
(*Wrist position*) 
pw,
(*Joint angles*) 
q1Sol,q2Sol,q3Sol,q4Sol,q5Sol,q6Sol,
(*Intermediate calculations*) 
L2,L3,L4,A2,
R03=Evaluate[(A0iall[[4]][[1;;3,1;;3]])/.params/.q1->q1temp/.q2->q2temp/.q3->q3temp],
T01=Evaluate[A0iall[[2]]/.params/.q1->q1temp],
phi,beta,gamma,eta,r,a1=a1/.params,a2=a2/.params,a3=a3/.params,d1=d1/.params,d4=d4/.params,d6=d6/.params,
(*List of joint angle solutions*) 
jointAngles123,q456Sol,allSolutions},{px,py,pz}=pe;
{q0,q1,q2,q3}=quat;
(*Define your robot's DH parameters here*) 
(* a1=a1/. params;a2=a2/. params;a3=a3/. params;
d1=d1/. params;d4=d4/. params;d6=d6/. params;*)
(*Step 2:Compute the Rotation Matrix from the Quaternion*) 
R={{1-2 (q2^2+q3^2),2 (q1 q2-q0 q3),2 (q1 q3+q0 q2)},{2 (q1 q2+q0 q3),1-2 (q1^2+q3^2),2 (q2 q3-q0 q1)},{2 (q1 q3-q0 q2),2 (q2 q3+q0 q1),1-2 (q1^2+q2^2)}};
(*Step 3:Compute the End-Effector Orientation Vectors*)
 ne=R[[All,1]];
se=R[[All,2]];
ae=R[[All,3]];
(*Step 4:Compute the Wrist Position*) 
pw={px,py,pz}-d6*ae;
(*Step 5:Compute q1*) 
q1Sol=ArcTan[pw[[2]],pw[[1]]];
q1Sol={q1Sol,q1Sol+Pi};
(*Two possible solutions*) 
(*Step 6:Compute q2 and q3 for each q1*)
 L2=a2;
L3=Sqrt[d4^2+a3^2];
A2=a3;
L4=Sqrt[A2^2+d4^2];
phi=ArcCos[(A2^2+L4^2-L3^2)/(2 A2 L4)];
(*Initialize list of joint angles*) 
jointAngles123={};
Do[
(*Transform pw to frame 1*) 
T01=T01/.q1temp->q1;
pw=Append[pw,1];
pw1=Inverse[T01].pw;
(*pw1=RotationMatrix[-q1,{0,0,1}].(pw-{a1,0,d1});*)
r=Sqrt[pw1[[1]]^2+pw1[[2]]^2];
beta=ArcTan[-pw1[[2]],pw1[[1]]];
gamma=ArcCos[(L2^2+r^2-L3^2)/(2 L2 r)];
q2ElbowUp=(Pi/2)-beta-gamma;
q2ElbowDown=(Pi/2)-beta+gamma;
eta=ArcCos[(L2^2+L4^2-r^2)/(2 L2 L4)];
q3ElbowUp=Pi-phi-eta;
q3ElbowDown=Pi-phi+eta;
(*Append both elbow up and elbow down solutions*)
 AppendTo[jointAngles123,{q1,q2ElbowUp,q3ElbowUp}];
AppendTo[jointAngles123,{q1,q2ElbowDown,q3ElbowDown}];,{q1,q1Sol}];
(*Step 7:Compute q4,q5,q6 for each set of q1,q2,q3*) 
q456Sol=Table[Module[{R01,R12,R23,R36,q4Up,q5Up,q6Up,q4Down,q5Down,q6Down,a33},{q1,q2,q3}=joint;
(*Compute the rotation matrix R0_3*)
(* R01=RotationMatrix[q1,{0,0,1}];
R12=RotationMatrix[q2,{0,1,0}];
R23=RotationMatrix[q3,{0,1,0}];
R03=R01.R12.R23;*)
R03=R03/.q1temp->q1/.q2temp->q2/.q3temp->q3;
R36=Transpose[R03].R;
a33=R36[[3,3]];
ifPositiveQ5=ArcTan[Sqrt[R36[[1,3]]^2+R36[[2,3]]^2],a33];
ifNegativeQ5=ArcTan[-Sqrt[R36[[1,3]]^2+R36[[2,3]]^2],a33];
(*Wrist up solution*)
q5Up=ifPositiveQ5;
q4Up=ArcTan[R36[[2,3]],R36[[1,3]]];
q6Up=ArcTan[R36[[3,2]],-R36[[3,1]]];
(*Wrist down solution*) 
q5Down=ifNegativeQ5;
q4Down=ArcTan[-R36[[2,3]],-R36[[1,3]]];
q6Down=ArcTan[-R36[[3,2]],R36[[3,1]]];
{{q4Up,q5Up,q6Up},{q4Down,q5Down,q6Down}}],{joint,jointAngles123}];
(*Step 8:Combine all solutions*)
 allSolutions=Flatten[Table[{Join[jointAngles123[[i]],q456Sol[[i,1]]],Join[jointAngles123[[i]],q456Sol[[i,2]]]},{i,Length[jointAngles123]}],1];
(*Return all feasible joint angle configurations*) 
allSolutions];