[SYSTEMML-621] Remove redundant nested error messages

[deroneriksson]

Addresses some redundant nested error messages for read, rand, and matrix statements.

Given the following DML:

a=read();
b=matrix();
c=rand(2,2);

This previously generated the following output:

ERROR a.dml line 1:0 unable to process builtin function expression read:ERROR: a.dml -- line 1, column 0 -- read method must have at least filename parameter
ERROR a.dml line 2:0 unable to process builtin function expression matrix:ERROR: a.dml -- line 2, column 0 -- for matrix statement, must specify at least 3 arguments (in order): data, rows, cols
ERROR a.dml line 3:0 unable to process builtin function expression rand:ERROR: a.dml -- line 3, column 0 -- for Rand Statement all arguments must be named parameters

--------------------------------------------------------------
The following 3 parse issues were encountered:
#1 a.dml [line 1:0] [Validation error] -> a=read();
   unable to process builtin function expression read:ERROR: a.dml -- line 1, column 0 -- read method must have at least filename parameter
#2 a.dml [line 2:0] [Validation error] -> b=matrix();
   unable to process builtin function expression matrix:ERROR: a.dml -- line 2, column 0 -- for matrix statement, must specify at least 3 arguments (in order): data, rows, cols
#3 a.dml [line 3:0] [Validation error] -> c=rand(2,2);
   unable to process builtin function expression rand:ERROR: a.dml -- line 3, column 0 -- for Rand Statement all arguments must be named parameters
--------------------------------------------------------------

With this PR it generates:

ERROR a.dml line 1:0 read method must have at least filename parameter
ERROR a.dml line 2:0 for matrix statement, must specify at least 3 arguments: data, rows, cols
ERROR a.dml line 3:0 for rand statement, all arguments must be named parameters

--------------------------------------------------------------
The following 3 parse issues were encountered:
#1 a.dml [line 1:0] [Validation error] -> a=read();
   read method must have at least filename parameter
#2 a.dml [line 2:0] [Validation error] -> b=matrix();
   for matrix statement, must specify at least 3 arguments: data, rows, cols
#3 a.dml [line 3:0] [Validation error] -> c=rand(2,2);
   for rand statement, all arguments must be named parameters
--------------------------------------------------------------

[gweidner]

Hi Deron - should this 'throw exception' comment also be removed similar to change made in line 278? Thanks, Glenn

[deroneriksson]

Good eye! Yes the comment should be removed too. I'll remove it.

[deroneriksson]

Obsolete comment removed.

[gweidner]

Thank you @deroneriksson for simplifying the error messages!

LGTM

[deroneriksson]

@gweidner Thanks for reviewing! I'll merge.