if the return error value is never to be a valid error, just remove the error definition in its signature

[AilinKid]

Enhancement

for some function signatures, if the return error value is never to be a valid error, just remove the error definition in its signature.

-func (*DataSource) buildIndexMergePartialPath(indexAccessPaths []*util.AccessPath) (*util.AccessPath, error) {
+func (*DataSource) buildIndexMergePartialPath(indexAccessPaths []*util.AccessPath) *util.AccessPath {
        if len(indexAccessPaths) == 1 {
-               return indexAccessPaths[0], nil
+               return indexAccessPaths[0]
        }
 
        minEstRowIndex := 0
@@ -401,7 +401,7 @@ func (*DataSource) buildIndexMergePartialPath(indexAccessPaths []*util.AccessPat
                        minEstRow = rc
                }
        }
-       return indexAccessPaths[minEstRowIndex], nil
+       return indexAccessPaths[minEstRowIndex]
 }