Fix bug in RightApproximationByAddM (list version)

[emerson-escolar]

Computing RightApproximationByAddM "for a list of modules and one module" on input where some module in the list has endomorphism algebra with nontrivial radical gives the following error message: "Error, no 1st choice method found for `FromEndMToHomMM' on 1 arguments." This pull request fixes that error.

The following code is a simple example for where an error occurs:

Q := Quiver(2, [[1,1,"a"], [1,2,"b"]]);
kQ := PathAlgebra(Rationals, Q);
AssignGeneratorVariables(kQ);
relations := [a^2];
gb := GBNPGroebnerBasis(relations, kQ);
I := Ideal(kQ, gb);
GroebnerBasis(I,gb);
A := kQ/I;

L := IndecProjectiveModules(A);
S := SimpleModules(A)[1];

RightApproximationByAddM(L, S);

Thanks to @ToshitakaAoki for discovering this bug.

[codecov[bot]]

Codecov Report

Merging #86 (92bdb48) into master (00bd470) will not change coverage. The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master      #86   +/-   ##
=======================================
  Coverage   60.72%   60.72%           
=======================================
  Files          74       74           
  Lines       22513    22513           
=======================================
  Hits        13670    13670           
  Misses       8843     8843           

Impacted Files	Coverage Δ
lib/modulehomalg.gi	69.46% <0.00%> (ø)

[sunnyquiver]

Thank you very much for fixing this bug.