Fix MinimalGeneratingSet for solvable non-pc groups

It could end up returning nothing and not invoking TryNextMethod().
This caused a failure in the hap test suite.

This is a recent regression in 4.12.0.

lib/grp.gi

@@ -112,16 +112,16 @@ InstallMethod(MinimalGeneratingSet,"test solvable and 2-generator noncyclic",
 function(G)
 local i;
   if not HasIsSolvableGroup(G) and IsSolvableGroup(G) and
-  CanEasilyComputePcgs(G)  then
+     CanEasilyComputePcgs(G) then
     # discovered solvable -- redo
     return MinimalGeneratingSet(G);
   elif not IsSolvableGroup(G) then
     if IsGroup(G) and (not IsCyclic(G)) and HasGeneratorsOfGroup(G)
         and Length(GeneratorsOfGroup(G)) = 2 then
       return GeneratorsOfGroup(G);
     fi;
-    TryNextMethod();
   fi;
+  TryNextMethod();
 end);
 
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